I can't stand Iain Lee or Callum.
Iain frequently says 'outrageous' things for effect and often goes too far. His behaviour with Callum wasn't the first time he has crossed the line and it won't be the last (though I wish BOTS would get rid of him).
I strongly suspect that Callum complained and demanded an apology. He doesn't appear to take criticism well and hasn't much in the way of a sense of humour. Once someone offends him (like Charlies nomination) he isn't going to forgive or forget.
I wouldn't want to be around either of them.