I don't think that's true. I cannot recall any evidence that Sulu was straight. He never had any relationships in the show that I can remember. Maybe some people assumed he was straight but without actual in-show evidence there's no reason for that assumption. A properly-written gay character isn't some swishy stereotype, it's a character that you can go decades without knowing the character is gay because it just never comes up.While the Sulu of the original TV series was depicted as being straight.
He did have a daughter, but without knowing more about her conception that doesn't mean he was straight. And his mirror universe evil twin was all over Uhura, but that is also not evidence about the real universe Sulu because 1) they don't have to be the same orientation, and 2) mirror universe might have not been a safe universe to be gay in so mirror Sulu would have had to hide it.
It's possible I've forgotten something relevant but I don't think so.
As to "twisting" Roddenberry's creation, every single element of the new movies have been a carefully crafted twisting of the original Star Trek designed to deconstruct everything that it was about. It's a little late to complain about it now.