When scum emphatically wants town to believe something, it seems worthwhile to reconsider that assumption. Your read of joth in lieu of his flip was that 2 per timeline was more likely. My view was that it was now less likely, because one of its main proponents turned out to be scum - I.e. a person with a vested interest in killing us.
It’s like if I believed, based on independent research, that alligators wouldn’t eat people and there was someone I trusted who strongly agreed with that assumption, then I found out that person was actually an alligator who ate people. It might cause me to re-examine.
Depending on the thing and the context, yeah, you're right. But on occassion, scum says something that they could only know because of info they have that town doesn't. In this case, part of the initial push on Joth was that he sounded a little bit too confident that it was 2-2, to the point that only someone on the scum team would know it with that level of certainty. So in this particular context, my confidence that it is 2-2 actually went up as a result of the flip.
Why do I think that is the case rather than what you said? Because of the way Joth defended himself. Most people who assumed 2-2 and/or sided with Joth were focused on "I/we didn't say it absolutely was 2-2" kind of arguments. To them, the issue was that they felt Ash was misrepresenting their statements. Joth agreed with that, but pushed back more on the point that assuming 2-2 was a reasonable and pro-town thing to do more than others. The focus their suggests that Joth knew he had used info that he had and town didn't and was getting pressure on it, and so in order to diffuse the point he needed to make people believe it was a towny thing for him to have done in the first place. Now I could be wrong about this, but would have to go back and read the whole day again to double check my memory, which I'm not going to do in twilight.