The reason people find it weird is that people who work in Hollywood and the Television industry have this weird etiquette where they won't criticise anyone else in case the company they work for wants to hire someone in the future and to prevent any bad press they receive doesn't hurt future job opportunities (It's annoying, and really fake but it's logical considering it's a large incestuous industry). The internet, however, is a much freer medium so criticising others is more of a free action. Gavin works for Rooster Teeth and Rooster Teeth have no plans of working with RWJ or PDP so throwing a couple of stray digs doesn't hurt any one. This makes open criticism from big names on the internet seem hostile when it's actually just natural, honest opinions. It's a comparison we make because it's our only pre-existing reference pool. When sycophants are the standard openly critical people get lumped in with the dickheads. Obviously there's more to it though. PDP and RWJ are acceptable targets.

EDIT: On the other hand, RT realises there's little crossover with their fans and also realises that there are an outspoken crowd of haters for these two. Open criticism of them is actually a solid business move as it seems inclusive to the bandwagon. They join the bandwagon, the bandwagon follows them. It's the exact reason Seth Rogen saying negative things about Justin Bieber on twitter gets 3k upvotes on reddit. Justin Bieber's an easy target. People who don't like him warm to Seth Rogen. Maybe a few more seats get filled at your local screening of The Interview. I'll admit this paragraph's a little cynical and probably somewhat bullshit. Probably should have stopped after the first.