Yes, using the abbreviation cf, which means ‘compare with’ or ‘by way of comparison’. There seems to be an implied link. Why do you think that there is not?
Is it that a padded bra is going to deceive a heartless womanizer who is trying to make it past the bra? He’s fooled into thinking her breasts are larger than they are. The bra is deceiving the gay (rake). Gay…deceiver. Seems pretty straightforward.
Actually it seems pretty convoluted. Why not use gay in its straightforward meaning? Especially since Powell uses it that way five other times in the book.
It’s possible that Gay Deceivers has a completely different origin that makes it just coincidental. But the phrase still doesn’t work for me in your interpretation. Falsies are deceivers that are gay; they aren’t designed to fend off gay deceivers.
Acronyms are a favorite form of folk etymology. Virtually none of them are ever true, and they’ve all been exhaustively studied. As has gay. I give you a 1000% guarantee that gay does not derive from an acronym, although it is obviously possible that somebody might have made an acronym from gay.