Such events are always multifaceted. To believe there was no financial motivation for John to rejoin in 1998 is asinine. Or to believe that his resignation post-2007 had nothing to do with him thinking he never had to work again for money. There can be a financial motivation this time around, too. Doesn't mean it is or has ever been his only motivation. Most people try to find a job that pays and is in some form fun, interesting or otherwise fullfilling to them. It's possible what John said to Rob Rule at the Soundgarden show was said in a playful manner, but still with an element of truth.
Rub Rule didn't know anything about Robert Hayes' death, even though John has extensively talked about it multiple times. He obviously doesn't know everything.
I believe his point about Anthony Kiedis though. It would explain the animosity between them in 1991, is consistent with AK's known character flaws and at the same time something they would have never discussed publicly.