That isn't proof. Why are fighters like Walters and Salido asking for more money than they're worth when it comes to Loma and nobody else? Walters admitted to asking for 1 million to fight Loma and this was when Loma was moving up to SFW, he hadn't even fought there yet. Salido was asking for the same for a rematch.
Now, I can only speculate (just as you are) that not many would be willing to fight Loma right now considering his last 4 opponents quit on him in between rounds and he's been on a tear for the last 4 years. They're weighing the risk vs reward and not liking their chances I'd imagine.