Anti-SLAPP has nothing to do with that case. "The South Butt" was actually producing and selling clothing with a logo/slogan very similar to TNF, but even then the two parties settled until "The South Butt" violated the agreement. Anti-SLAPP is about protecting journalism/protest/speech, not for-profit competitors using another brand's branding (even if in parody).
If they had just stuck to the name, "The South Butt," I genuinely believe they would have been fine. It is the inverted logo and "Never Stop Relaxing" that caused them to lose. Parody protections have always been curtailed for commercial competition.
And not specifically discussing the South Butt case. The idea that lawsuits are just tweets with a filing fee (i.e. a way to spend money in a public forum to try and promote your idea of what's right) translates almost directly to a SLAPP suit.
You are quite accurate about the specific South Butt case - but I was trying to be more general.
Wikipedia Article:
https://en.wikipedia.org/wiki/The_South_Butt
If they had just stuck to the name, "The South Butt," I genuinely believe they would have been fine. It is the inverted logo and "Never Stop Relaxing" that caused them to lose. Parody protections have always been curtailed for commercial competition.