I can't imagine moving to a new state, much less CA, without a real plan. It's not your job to save him from himself.
Latest update from cousin's son: he has moved on to cousin in Irvine (who currently has 3 people in her apartment that's designed for 2, so she's also going to be a non-starter for him). I 'm really intrigued (in a watch at a distance and do not engage way) how he thinks this is going to work out. Approach semi-distant relatives you've never met who live in a couple of the most expensive cities in SoCal in the hopes that someone lets you...live on their couch while you magically find a place you can afford to live and a job good enough to support yourself? If I wasn't afraid of encouraging them, I'd ask his mom if there's ANY plan at all.
Sorry to hear how DONE everybody is. Hope you all get a recharge very soon.