Normally I would think he was not serious - he's a stand-up comedian and they're supposed to say surprising things - but I actually think he is serious and who could blame him? Ewan McGregor really is a beautiful man. And I am really impressed that Louis C. K. can stand there in front of an audience and admit this. How refreshing.
McGregor himself has no trouble playing gay:
And nobody can wear a kilt like Ewan McGregor.
It always amazes me how much kilts look like the skirts of the Catholic school uniforms I wore in grammar school. These schools had no pretensions of being Scottish but for some reason that pleated & plaid look was all the rage.