The word equality is in there but we aren't talking about equality in flag waving. That's protected by your first amendment right and if you wanted to wave a straight pride flag go right ahead. The FO may not want you to wave it in the SG area and they have the right to remove you for violating their rules.

Ultimately the pride flag is the recognized symbol of the LGBTQ Rights movement and the league as a whole has aligned itself with this movement to the point where the teams have added it to their logo for pride nights and even to their captains arm band on occasion.

As someone else pointed out. Its an accepted position of the league and as such waving it in the supporters section is tantamount to shouting "DON'T CROSS THE LINE" or "GIVE RACISM A RED" . In this context the "straight pride flag" does not pass this test and could be considered "political" and outside the message the club wants to portray. Additionally it would seem that such a flag would only exist to provoke people (another poster in this thread basically said that he just wanted "to see what people would say") at best there really would be no clear political meaning or "movement" and worst it would be there only to provoke a negative response.

EDIT: Added some lines at the end.