Cameron is an asshole, it's not some industry secret. James Horner even refused to work with him after Aliens until Cameron apologized and came begging for forgiveness prior to Titanic. His on-set tirades are pretty well known, in fact they make up most of the supplemental material on the Aliens disc set. I've got some industry acquaintances that have worked with Cameron, and also state he's a pretty big asshole.
The caveat is that the guy is a technical genius, and he really knows his shit. The vast majority of the time, when he calls a crew member out on something - it's because he's right. It's just the guy has never heard of tact.
That said, TMZ is a tabloid full of antagonistic assholes, so I'm pretty sure it's a LITTLE BIT FROM COLUMN A AND A LITTLE BIT FROM COLUMN B.