He's retiring the same way Conor retired when he didn't get his way at UFV 200. It's just a glorified sulk, he's not going to throw in the towel while he's still relatively young, uninjured and holding an interim belt.
He should just fight Holloway to keep active. If Conor beats Alvarez, Conor will have to drop the 145 belt and Aldo will become champ by default. Then he could move up and fight McGregor for the 155 strap.
If Conor loses to Alvarez, he'll be forced to defend his 145 belt against Also. Either way, he can fight Conor after their next fight so long as he gets past Holloway or Pettis.
I get why he's upset, but if getting the belt and fighting Conor again are the only things that mean anything to him, he'll take another fight.
We've all seen how having a tanty and threatening to retire has worked in the past for fighters....if Conor doesn't what he wants with that angle, there's no way Jose does.