There's a lot of contradicting points here.
Tyre pressure not a Sporting Regulation or Technical Regulation. It's a Technical Directive from Pirelli to the FIA. Which it itself is utterly confusing.
The FIA knew from the start and didn't black flag the Mercedes or demand a tyre change. Potentially pointing to sporting issue that can be contested.
I can't see why it would be done on purpose by such varying amounts. It's a mess that I really hope will have a definitive answer. If they get DSQ, which I can accept, why were they allowed to even race with this known from the start? That would be another mess up from the FIA in my eyes, you can't have the winner not winning from a issue known about from before the race, it's not fair on the fans.