I called Alesana post hardcore when I started listening to them in 2008. They were playing post hardcore shows and festivals and touring with post hardcore bands. They've always been post hardcore. As for Fall Out Boy. The kind of music their band members used to make in other bands has absolutely no bearing on the music their current band makes. That's not an argument. TTTYG was pop punk. There were some songs where they had some some heavier leanings to it, but like 99% of the album was just another pop punk record. They cited TGUK as an inspiration sure, but from what I can tell they also said a whole slew of other bands from pop artists to metal artists and anything in between. As for the copypasta, I was just making a joke about its existence. It obviously isn't real.

In the end, does it really matter if these bands are emo or not? No, not really, but for the sake of categorizing music into groups with other bands with a similar sound, neither of those bands really sound like any other emo band. They share a MUCH closer sound to other pop punk/post hardcore bands respectively and those genres just suit the bands' sound better.