Because he needs a gig, I would assume. The question is, (maybe your question), why would A., any GM hire the notoriously difficult-to-work-for ex-Current TV, ex-MSNBC, ex-ESPN cable/network, (briefly, NBC Sports Sunday Night Football) gadfly?
Maybe Olbermann likes the Bay Area. Maybe he'd be willing to work for a bag of peanuts, (by his standards), although I'm sure he has a few shekels in the bank.
If the bigwig pulls this off, and there's no guarantee the duo were even talking about a gig, then I'd bet this would and could be a major splash. Risky too. I don't know, maybe Keitho was in town to catch a Warriors game, (I doubt that, really.)