Honestly, I am most worried about Sabah coming to the conclusion that Joe is a cape not Apeiron but most likely a thinker.
My thought process is Sabah knew Joe from college she knows how he looked and acted She'd be able to tell that he both acts different and is far more physically fit, while most people would probably contribute this to joe changed after not seeing him for so long, I could see Sabah viewing it as suspicious, Sabah believes that no normal person could set up the event and have it succeed, So If she finds that Joe set up the event and that it's succeeding, her conclusion will likely be that Joe is a thinker and that he is working with Garment she's already convinced that Garment is coming after her and thinks that there someone behind it, her coming to the conclusion that it's Joe and that he is after her personally for not going out with him would make sense from her perspective.
From there, things could go really bad really fast, no cape attack necessary, the worst possible outcome would probably be her accusing Joe of being a thinker on live television.
One of the best tropes in stories involving secret identities is that of mistaken identity.
What if Sabah correctly deduces that Joe has superhuman abilities but completely misidentifies his masked identity?
She might believe him to be Grue or a member of the E88 trying to recruit Garment for his evil gang.
Or, given that Joe and company can now jump in and out of the workshop from any available door, it is very possible that she might see one member of the Forge enter a room/closet and a different one emerge.
She knows that Joe was an engineering student. If she observes him performing a task at supernatural speed then she could believe him to be Fleet.
Joe could theoretically be Matrix, Tetra, or another member of the Forge with the right changer/breaker abilities.
However, I think it would be hilarious if Sabah mistakenly deduces that Joe and Survey are the same person.
Brockton already has a parahuman, Circus, who is genderfluid (although I don't know how well know that fact is?).
If Sabah was to pursue Joe in order to have a confrontation, only to see him duck into a closet then for Survey to emerge... Sabah could mentally review the charity event and realize that she never saw Joe and Survey simultaneously at any time that evening.
Cue romantic angst and drama.
Hopefully Sabah will eventually run into Flechette and the two can bond while pining over failed relationship and could-have-beens.