Is it rude of me to ask a celebrity a favor? (favor I'd ask in details)?

I'm meeting John Barrowman next month and I was going to ask him if he can send a tweet to Ellen Degeneres using #colleenonellen in honor of a classmate of mine who passed away in October (this video explains it all: https://www.youtube.com/watch?v=KJrb7p116cU ) and I feel bad asking him but (I feel) Ellen is ignoring everything we've sent her so I've been trying to have celebrities tweet her but they're ignoring me too (I'm not really shocked or upset)...is it rude of me to ask him to do this?