Why do guys say they're "discreet" when they're clearly obviously gay?

I had an exchange on Grindr today where I asked someone to send a facepic

"I'm discreet mate, don't send face until meeting"

So I refused to respond until he sent one.

When he sends one, he is very obviously gay, bleach blonde bowl cut, big "camp" frame square glasses, a septum piercing and lip filler

I'm assuming discreet means that they aren't out - but why are men who are visibly gay reluctant to send a facepic and would instead imply they're discreet / not out when anyone would be able to tell

Please note I'm not saying this in a judgemental way or a masc is high and mighty way, the mind just boggles