Obviously Lernt is serious, and I don’t see why he’s being dragged through the coals. There are legitimate, undeniable similarities, to say nothing of how programmed certain people seem to be from the groups mentioned.
If Lev Tahor gets big enough, will it become wrong to criticize them too? If they set up in towns and colleges across the country to convert people to Lev Tahor, will we have to call that “good?” A cult cannot be beyond criticism just because they convinced enough people to join them.
The only point I can see in being critical is that if we start making thread targeting Chabad instead of just replying to threads made by Lubavitchers, we start to look like the Litvish version of Chabad Forum sites that just bash on everyone. Still, I don’t think Lernt should be singled out just because we want to keep the moral high ground. He brought up specific practices and similarities, not just random, baseless insults.