First off, the only reason why people think Federline is such a complete dirtbag is because the media told you to believe that he's a complete dirtbag. You have it from people that know him personally saying that as a person and as a father, he's not so bad.

That doesn't necessarily mean that if Britney had been totally healthy and firing on all cylinders that Kevin would be the one the kids got handed to. Maybe he would, maybe he wouldn't, we can't possibly know.
Wasn't the only reason for a battle because Kevin requestion FULL custody? Whatever battle they were having, either way...it was never going to result in him not seeing those boys.