I know nothing I say would stop you from being a fuckwit asshole, so I won't even try, but if you're going to be like this please at least know the difference between a noun and a pronoun.
Your "joke" (which is really not a joke and just bigotry, really, but you seem like a lost cause so I won't bother going on about it) doesn't make sense because in no context would anyone say "they in the middle". They/them are pronouns, typically for people who identify as non-binary. You'd say "non-binary person in the middle" or "enby in the middle". Saying "they in the middle" is equivalent to "he in the middle", not "man in the middle".
This is, of course, disregarding the fact that no one actually gives a fuck if you use the phrase "man in the middle". I swear I see more dumbass "jokes" like this than actual attempts to use inclusive language. At this point, the transphobia is almost a secondary nuisance compared to the complete lack of any comedic skills.