Straight guy here, so take whatever I say with a grain of salt.

I agree with the author's view that the sexual orientation of the performer should have no bearing on the casting process. As long as the production in question is doing its best to portray LGBTQ+ characters as human beings (and not just sexual orientations, which can lead to mere caricature), then the part should go to the person who gives the best audition, full stop. To give it to an LGBTQ+ person who gave an inferior audition just to satisfy a political objective doesn't do anyone any favors.

Moreover, while I would never want to see an LGBTQ+ actor denied any role because of their orientation/identity, I think there can be a particular value in having a straight actor portray a non-straight character, as they bring their straight audience with them on a journey they weren't expecting to take.