Even if the "mosrim" were completely in the wrong Halachically, mob violence is completely unacceptable. Full stop.
It shouldn't take a lamdan to realize how this is wrong in many levels.
100% agree that attacking them is/was/will always be wrong on all fronts.
However, that doesn't make what these 2 guys were doing morally or ethically right - and I'll say it the opposite way than you did: even if by the letter of the law (meaning halachah) they are not violating anything it doesn't mean it was the right and correct thing to do. And if I may humbly add, they don't deserve to be defended. 2 wrongs don't make a right.
I don't know enough about them having only recently discovered their existence but it seems to me that they've been raising the ire of certain communities way before COVID came around and with very not pure and holy intentions. So those that are saying that now with their COVID reportings they were doing it solely in the name of saving lives, I'm sorry but I'm having a very hard time believing that all of a sudden these guys became purely altruistic.
Just my personal observations.