Wow! That took some nerve! I can't believe how people are anymore. No manners. I'm sure I would have been stunned too. BUT I really think you should go back (or call) the Mgr. They should know about his behavior. I have heard the phrase "clean it up" but who would have thought he'd just take your baby like that???? Either way he should have let
you bring your baby in and then it would have given you time to think about what he was offering to do!

My Max wouldn't like someone just picking him up and taking him like that

That would have freaked him out! You didn't do anything wrong sweetie - HE did!