We are currently a long, long, long, long, long, loooooong way from having to worry about positive discrimination towards LGBTQ actors. For starters, there just aren't that many roles being written.The problem would come if it were exclusively LGBT actors that got LGBT roles. That would then be discrimination in the same way it would be discriminating to ban LGBT actors from playing straight.
Having to hold back now because of some hypothetical far off time where gays rule the earth is just ludicrous. Indeed, I'm old enough to remember the same argument being made about black actors being given more prominent roles than just token characters...and here we are in the future and no shortage of white people in entertainment.