Have you read any of Fry's autobiographies? He is triggered, as the kids would call it, by the mere reference to warmed milk. He demands no-one speaks of, say, bread and milk in his presence. And then he complains rape victims are over-sensitive.
"He ran a thumb between Clara's lips ... Of honey and sweet warm milk.” “Aniseed?” “If you like aniseed it will..."
There's nothing else relevant except your comment on google or Bing.
I also found comments on Stephen Fry's site about QI XL from 07/03/09 [1] where bread and milk was apparently discussed, with no mention of Fry going off the handles over the subject he himself apparently introduced. And the comments themselves includes multiple mentions and have been left up.
(EDIT: The episode in question is season 6, episode 11, Films and Fame. It doesn't mention "warm milk" but it does go on quite a bit about bread and milk which GP also claims he has an issue with. Stephen Fry asks what you should not feed a Porcupine; Emma Thompson, who is a close friend of his and certainly would know if this was a no-go area, answers "bread and milk" and Stephen Fry repeats her answer, and David Mitchell and Alan Davies then gets into an extended argument about bread and milk. Here is where it starts [2]. That episode also includes a fantastic segment with discussion about the late Alan Rickmann, btw., where John Sessions does some fantastic impressions of him)
Barring evidence to the contrary, I'm going to assume that if there's a mention of this in his autobiography, that it's meant as a dry joke or exaggeration for comedic effect, which would fit very much into how Fry writes and talks.
[1] http://archive.stephenfry.com/forum/topic/qi-xl-070309-bread...
Nigel Slater mentions in his autobiography the revolting luke-warm milk served at UK schools in the 70s.
https://www.goodreads.com/book/show/71969.Toast
(Ctrl F for milk)
All of this sjw/triggering stuff is nonsensical and baffling, but it is also baffling that we live in a society where attacks on a person's character and history somehow influence the validity of what that person says. Anyone has the capacity to say something that is true. If a murderer stated that the Moon orbits the Earth, you would have a hard time convincing rational people not to listen just because he was an immoral person.
Ultimately, it is fallacious to disagree with someone just because you don't like them or because they are hypocrites. Hypocrisy doesn't make a statement or set of statements true or false.
Attacking a person's character or history instead of attacking their argument represents an act of dissociation or insansity, either of which would equal triggering in the magnitude of its infantile absurdity.
I find this quite amusing as the end of a comment that started with an attack on someones character.