Second Genders weren't really that big of a deal.
With quirks providing as much trouble as it did help, people didn't really have time to care or discriminate people based off of these second genders.
Alpha, Beta, Omega.
Everyone still acted the same, they were all human beings, after all.
Though, Izuku Midoriya always thought of second genders in a certain way. He observed things closely and knew that he had to hide who he was.
He didn't need anyone knowing who he really was.
-Blood
-Descriptions of Violence
-Gay stuff