Given what a terrible father Gabriel is, I think it would be VERY funny if deep in his Hawkmoth hideout he has one of those "WHO IS CHAT NOIR?" corkboards with all the red string and pictures and information tied together.
And it's got like "best friend: Nino" and "close friends with Marinette?" and Adrien's homeroom teacher and Adrien's general practitioner and Adrien's dentist and Adrien's birthday and favorite foods and hobbies and interests
And all of this information points back to this image of Chat Noir in the center with "WHO?????????" written across him in red sharpie while Gabriel bangs his fists against the board screaming "Who could this boy possibly be?!??!"
I mean.
It’s canon that he knows that every. single. miraculous. holder. whose identity he knows is closely associated with his son.
It’s canon that he used his son to get them all in the same place for easy pickings.