If you mean why the family and staff allowed him to stay around well there are a number of reasons. Mainly I think it is because he has shown himself from time to time to be human wishing to be loved and to love (like when his homosexuality officialy became common knowledge) or for something he did or can do (examples: his cricket skills, saving Edith in the fire, or when he, although accidentally, exposed Nanny West's treatment of Sybbie, and when Mary asked him to get the butler Stowell in trouble because of his rudeness toward Tom).
If you indeed mean why he was allowed to stay around despite his 'mischief', I agree with the person above me. Every time they were about to kick him out, something happened that put him in the family's good books again. I'm also not sure whether the family is aware of how nasty he can be to the other members of staff, and I don't think anyone apart from Molesley knew he was threatening Baxter either. So a lot of the bad things we see him do just aren't known to the family. For example, when he locked away Isis, what we as an audience saw was him locking her away to his own advantages, but the family only saw him staying up all night to go looking for her, so their perception is very different. And even if the staff are aware of everything he gets up to, I don't think they're allowed to kick people out.
If you meant why they tolerated him despite his homosexuality when everyone else around that time was very much homophobic, now that is an interesting question to me. In season 3 we only see Carson and Alfred (and to some extent Jimmy) repulsed by it, but his Lordship and Ms. Hughes are very ok with it, as are Anna and Bates. The point however is that in that time it wasn't just very conservative people who were against it, but the kind people weren't always very understanding either. So I've always found it a bit weird that so many people were ok with it, seems a bit anachronistic. I mean obviously they should be ok with it as should anyone, but it seemed a bit odd given the time period.
As in any workplace, there will always be an inexplicable slimeball who just seems to survive being sacked, despite their behavior - we've all experienced this.
With regard to homosexuality, the upper classes have always exhibited a very blasé attitude to sexuality in general (much more so than the reactionary working classes and prudish middle classes), because same sex relations were (and sometimes still are) often a part of growing up in same sex boarding schools. The mantra tended to be that as long as you marry well and produce an heir at all costs, whatever extra dalliances you get up to in private are no one's business. That's why Robert doesn't particularly give a stuff about it.
Male homosexuality was tolerated in servants - and only in servants - and only in male servants. In fact, at the turn of the 20th century, the Royal family would only hire homosexuals for service as footmen. There were two reasons: First, they were unlikely to leave to get married. Second, they were not likely to get a maid in "trouble" - that is, pregnant. So in the household of a member of the upper aristocracy (it is debatable whether the Crawley's would fit this description) a homosexual footman would be the norm, rather than the exception.
Also, in every workplace, there are ******* (chose your favorite term) who managed to hang on and get promoted depsite their lack of character, abilities, and achievements.
That does make sense, thank you random wikia contributer and Wva! Wva, do you by any chance have a source for this information that at the turn of the century they would only hire gay footmen? It sounds very interesting and I would like to read more about it!
It is briefly mentioned in "At Home with the Queen", by Brian Hoey. However, it is only two sentences.
despite the fact that Thomas is quite nasty towards the other members of staff (but not towards all e.g. he seems to have a nice relationship with Mrs. Hughes and Daisy), Thomas is good at his job. He's a great valet, as well as skilled enough to also become the first butler (since he will never get married, he could vote his life to the service of the family).
Regarding his homosexuality, I agree with those before me that said that only "inferior" classes had a particular aversion, because basically they did not understand what it was (besides the various religious reasons). Just think of all those noble, even in the royal family, homosexuals. Or to bohemian artists, like those of Bloombsury club (which included Virginia Woolf, Edward M. Forster and others -now publicly known as- homosexuals and bisexuals). And to respond to Fellowes, when he said that Thomas could never find love seeing the historical period, I suggest him to read about all those gays and lesbians in history, and in particular, during the early 900, before the rise of Nazis, Berlin had clubs dedicated entirely to homosexuals, male and female, as you can see in the BBC move "Christopher and his kind" based on the novel from C. Isherwood. The same Italy was a tourist destination for gays (a bit 'as now islands like Mykonos or Ibiza) so it should come up with more excuses to make Thomas the devil. Obviously he could not marry - this would anacronistico- or live peacefully in the sunlight, but finding someone who love him is not that impossible.
Then Thomas also has made many positive actions for the family: he saved lady Edith from the fire, become attached to little Sibby and saved her for the witchy nanny, had a good relationship with Lady Sybil (and by the way tom it mourned her death, she probably also knew of the his homosexuality) and, again, he's good at his job as valet, so why they should cast him out?
What do you think?