The irony is pretty silly :-D
But at the same time, it still kinda makes sense to me. My guess it that TBTB is the headliner, and if they're actually that terrible to their fans, it could easily be a justifiable business move on the other band's part to leave the tour. Most of us will agree that bands airing out their dirty laundry in public only makes everyone look bad, but their actual (devoted?) fanbase would probably disagree.
I know if an artist I respected did this, I'd give them the benefit of the doubt and believe their assessment.
There have been PLENTY of shows/tours where we didn't agree with the way another band was acting but we'd never cancel a show/shows because of it. We were also never a band that would cancel or complain due to a lack of draw. There were times where some of us were literally sick all day or our van broke down and we'd still find a way to make it to the show and play a set for however many people wanted to see us play. I don't know, I'm not hating on them because I certainly don't know the full situation, however, airing out the dirty laundry between bands is never good policy because it just looks petty. My advice to this band, or any band, don't cancel shows that you can play. You're losing money, you may be losing fans, and you're definitely losing the experience of playing shows.