You're claiming the libertarians the person you replied to aren't (real) libertarians by implication that the group he was referring to aren't (real) libertaria

You're claiming the libertarians the person you replied to aren't (real) libertarians by implication that the group he was referring to aren't (real) libertarians. It's like a christian claiming a lutheran doesn't practice christianity, i.e., it's a "no true scotsman" fallacy.