Well, they know they can get something like $150M relocation fee. So even if they really want the Coyotes to stay, I don't think they are willing to let that much free cash flow to get by them.
If A is the expansion fee for a given market, B is the relocation fee, and C is the ongoing cost to keep the Coyotes alive, then the team will only move when B+C is greater than A.
When we're talking $500m alone for a crappy market like Vegas, it's clear the owners have $$$ signs in their eyes. Bettman will look to protect those revenue streams, as they do not have to be shared with the players. Cash money.
Even for "free" or close to it, it's not a slam dunk that he'd take the team. But he is one of the few wealthy businessmen in the valley that has pro sports chops, and could conceivably turn around the Coyotes.