What do you expect to gain in doing this?? They don’t need to be told this, and telling them this is bullying. Are you actually trying to hurt them emotionally?? Because telling them this is just cruel. You’re obviously a lot taller than those you’re telling this to, and telling shorter men/guys that they “won’t have a chance” with the opposite sex all over their height is just despicable
Yes, reading the room is still required, and then maybe explaining the comeback afterwards because usually if they’re dumb enough to just blurt out that sort of thing they’ll need it.