I don't know where it's coming from that Padilla won't be able to question Casey. Padilla and his crew can theoretically ask Casey a billion and a half things if that's what they want to do (unless there's some sort of binding agreement subject to penalties for breach to prevent this - and I'm not aware of one). Of course, Casey's not obligated to respond, but that's another issue. And in any event, this has no bearing on Padilla's real purpose in this case, which in all likelihood, is about making money, either through some book or media deal, or some other such thing that I can't think of.
The idea that Padilla's here to get the truth out of Casey is laughable. But I don't hold it against Padilla if his intentions truly are limited to financial gain. That's the way things work. In that respect, he's no different than any other bounty hunter or bondsperson; they're all in it to put food on the table and upgrade their refrigerators.
I'm also not so sure about the relationship between Padilla and Baez, and wouldn't be surprised if Padilla's people try to steer Casey to another attorney; an attorney aligned with the Padillas, either socially or professionally. It's a cutthroat world.
Just speculatin'.