She’s a bit on the heavy side. 
She was a standup comic at the beginning of her career and then again in the last few years, an awards show host, actress, broadway performer and a number of other things I’m forgetting details on at the moment. Make fun of her for being a bitch and hard to get along with all you want, but suggesting she physically couldn’t do the show is ludicrous.
Maybe she could do it, but I’m sure she’d prefer not to, to quote Crispin Glover.
Word. I like Rosie O’Donnell, but it seems like in recent years when she’s brought on board to a project with high hopes and the intention of making it better, the exact opposite happens. Consider The View and McCall’s magazine.
By Golly, that’s the Anointed One: Crispin Glover as TPIR host! Can’t you just see him fending off the Ultra Hug-n-Kiss Bob contingent? Come On Dowwwnnnnnn!