User blog comment:HanataSanchou/Important Takeaways from Ch. 805/@comment-5869646-20151029170511/@comment-26082375-20151029181130

Law's comment before taking down Trebol was more along the lines of "I am also the captain of my own ship. If I left [both Doflamingo and Trebol] to Mugiwara-ya, I wouldn't be able to face them." It's an issue of the pride of being a captain, not about entrusting his crew to Luffy.

He most likely didn't expect to see his crew again because he didn't expect to survive the clash with Doflamingo, and his original plan for Kaido is pretty much in smithereens thanks to Luffy. I'm guessing either he came up with a new plan or is just making stuff up as they go, now that he's more familiar with how Luffy works.

As for why he sent his crew off to Zou, could be as Kage said: to keep them safe. It doesn't sound like he knew exactly when he was leaving Punk Hazard, since the Straw Hats showed up there out of pure coincidence and he spontaneously decided to ally with them. Bepo's a Mink, which would make entry into Zou less of a problem, and Zou can't be found with normal Log Poses, which gives some degree of protection. Then again, Jack seems to have found it no problem, so I dunno.