Pronouns in German is weird. sie and Sie have different meaning depending on the form of verb and capitalization. I kinda like the French way of speaking - je, tu, il, elle, nous, vous, ils, elles.
In Dutch "they/them" is "zij". Which is very annoying, because "she" is also "zij".
Which means the Dutch genderless pronoun has mostly become "hen", which is "them" in the dative (3rd) case, which is only rarely used otherwise, and thus available.
No they say it because they want to objectify and demean you. I knew a guy like this and it had nothing to do with sticking to the binary and everything to do with making people feel bad for being different.