Actually, paypal are idiots. Half the stuff they process for, they do not understand. You need to explain to them why cutting off accounts is the wrong thing to do and how this WILL affect them if they continue to do so on mere whims. File lockers are a perfectly legitimate business.
The only reason this guy gives Dropbox a pass and no one else is because:
A) He can't find shit on DB yet; but I know there's tons of warez content on DB. It's just not as out in the open as the rest are.
B) He probably uses it personally.
Mediafire is a perfectly legitimate business, has been, and will always be. Yet he's targeting them because, according to him, 'their model encourages copyright violation and child porn uploads'. He started out with a mission to cut off hosts that were apparently a magnet for child porn. But that mission has quickly changed into a very simple one - doing what he must so his company can stop losing money that it apparently loses due to piracy. Well I've got news for him - piss off these 'warez people' and you're only going to see more of your stuff pirated in retaliation. This isn't something far fetched. It will happen, and he'll wish he hadn't taken up on this wild goose chase.
BUT, I bid him good luck in what he's doing. He'll need tons of it in the coming days. New comers in the filehost industry are no big deal to take down.