This is a genuinely clever reply.

I do wonder what a linguist would suggest about these two uses, though. English is a language in which context often changes outcomes.

It’s clever if you’ve never heard of context.

It's not clever if you've never heard a joke.

It's neutral referring to groups, not individuals.

If you approach a group and say "How are you guys?" it doesn't imply an all-male group.

Depends which register of english.

If I'm in a mixed group down the pub I won't at all be surprised if somebody (usually female) walks up to the table and says "hey guys" as a greeting, intending to include male, female and enby members of said group.

If I'm on the internet I'm not going to try and use "guys" as gender neutral because I fully expect I'd be misunderstood by a decent percentage of people reading if I did.

So I wouldn't say people are necessarily pretending, it's entirely possible they're just used to it being neutral and forgetting that for a bunch of people it very much isn't.

That's socially though - when talking about people I've slept with, I acknowledge I'd expect people to read 'guys' as only referencing the male-identified ones. Though I'm more likely to use 'dudes' for that purpose myself, because confusion around 'guys' can go in both directions.

Point taken.

There's a difference though between "guys" as an address (which is used by plenty of female-only groups as well) and "guys" as a noun.