In defense of trekkies and geeks everywhere: People don’t become immersed in shitty, nonsensical scifi or fantasies that lack cohesion and the attention to detail required to sustain true geek fandom. Game of Thrones was so popular as a book series precisely because George R R. Martin paid the attention to detail to make sure that The Hound wasn’t in two places at once, and the number of Redwyne children was consistent, etc.
Star Trek has such a geek-fanbase. We care about the consistency, and putting a human hijabi on the bridge would call into question much of the perception the series has given for the future history of religion.
An alien hijabi would be fine and present no such problem. But that’s not what pro-Trek hijabi advocates we’re pushing for, and might be insulting to those who want a hijabi helmsmen.