Well, now she knows when he's coming! She tweeted this on Wednesday:
The latest word on @ItsTheSituation is that we r starting to rehearse early next week! Yay! So excited! Finally!!!!Given that the show starts September 20th that means they will have at most 6 days of practice!
Obviously Mike is fit (and abdominal strength is an important part of dancing!) but he has very little time to learn the basics.
I suspect he'll have a reasonably large fan base so may not be at risk early on, but it does seem a little unfair to Karina.