tl;dr:
YHM stated they had a no questions warranty, up to and including breaking their suppressor the first time. Turns out they have a lot of questions and make you jump through hoops now.
I’m with you, if you bought one under their warranty, they should honor that warranty. If they want to change the warranty, then change it and give a date that the change happens. It’s not fair if that’s part of why you bought their product in the first place.If I had bought a suppressor under the no questions asked warranty and that was a significant part of my decision to purchase I'd be livid right now.
As it is, my previous distaste for YHM has now become outright avoidance. Willingness to go back on the promises made to people who you already took money from based on those promises shows a definite character to how you do business.