Warning the following contains spoilers for 90 Day Fiancé: B90 Strikes Back. Read at your own risk!
90 Day Fiancé: B90 Strikes Back was advertised as a chance for the cast of 90 Day Fiancé: Before the 90 Days Season 4 to "clap back" at all their critics, and 90% of the spinoff has been just that. Some participants have even found a way to laugh at some of their darkest moments, though that's not the case with everyone.
David Murphey is still very clearly working on some of the things that happened with his Ukrainian girlfriend Lana in Season 4, and it's not quite a subject he's ready to laugh at yet. I can't hold it against him, since he had an online relationship with Lana for close to 7 years. The collapse of that relationship would be painful no matter the circumstances, and it's clear David believed there was something between them.
The problem is that David is in the minority of that opinion, and much of the 90 Day Fiancé fandom spent David's season going on about the sheer wackiness of the relationship. This isn't special to David, as everyone has taken their lumps on B90 Strikes Back, but they all have some level of closure in their situations. As David pointed out in a recent episode, he and Lana are not officially broken up but do not talk nearly as much as they used to.
That update is quite a turnaround from the tell-all specials, where David went to war against Big Ed Brown and others challenging whether his engagement with Lana was genuine. David took offense to the suggestion that Lana was scamming him, so it's not hard to understand that he'd be as equally mad reading the same from strangers.
Most of David's remarks to the tweets on his relationship are him defending himself or getting angry at what the people said to him. It's tough to watch as a fan of the franchise, and a bit sad as well to watch David continually take his lumps as he slowly works towards the end of his relationship with Lana. There's no "clapping back" from David in my opinion, and it's just creating more fodder for the more brutal fans to continually take shots at him.
All that kind of defeats the purpose of 90 Day Fiancé: B90 Strikes Back, and makes me wonder if David should have been excluded from the commentary. In fairness to TLC, he's not the only one who had his relationship head south. In fact, that's the story for a majority of the show's participants. The others all seem to take the moments and comments in stride, so perhaps David could learn to just laugh at the situation a bit more even if it does still hurt.