The trouble is, either way he is sitting in a tub of fail. I'm assuming it's a hoax; if it is, it's something that has already been perfected by Andy Kaufman, and more recently riffed on by Sasha Baron Cohen. Phoenix and Affleck are going to look like YouTube amateurs in comparison. Plus, nobody really cared enough about Joaquin Phoenix in the first place for this meltdown to have any real impact.
At least with a Crispin Glover, you got some entertainment value with the oddball behavior. All we're getting here is a timid impression of a wannabee Jim Morrison. I had at least two friends in high school/college who went through that phase, and they certainly didn't deserve to be recorded while they were flipping out. One of them ended up taking a brief vacation in a mental ward.
If he really is cracking up, his "friend" Affleck should be shot for participating in this exploitation of his meltdown. If Crazy Johnny says "film me while I jump off this bridge," you don't pick up your camera. You try to talk him off the bridge.
Either way, I say bibble, bibble bibble, bibble bibble.