I'll do some more arm chair quarterbacking...
I've been jet skiing. The only jet skiing I'm familiar with is having fun within a particular area. It sounds like this guy used the jet ski for non-trivial transportation. Is that common in that area near Catalina Island? That sounds like a dumb thing to do in the ocean. After all, it is the ocean, not a lake.
Thoughts:
-Walkie-talkie to your friends boat? (10-35 mile range over water)
-spare gas in bottle? (bottle $10 gas $4 getting home safe? Priceless)
The article says he was outside of visual and radio contact from his friends (at least their radios). Also, in my opinion, a "fun" jet ski trip that requires spare fuel is a trip that should not be taken.