” a certain person decided were all kofrim BEFORE gimmel tammuz ”
Why does that even matter? If people claim we’re in a state of Geula when none of the criteria are met, they have to expect to be accused of kefira.
I will say, many of the Dati Leumim make basically the exact same claim (as you’ve seen here even on this thread) with far less backlash. I do think Chabad is a little unfairly singled out in that sense.