Well let's look at the three main "gay space marines" that play a role in today's industry.
Master Chief - The original space action hero. Sure concepts were borrowed heavily from Starship Troopers and Aliens, but Master Chief was the Neo of Action Games. And Is arguably the first of this template. Now as for his sexuality, It frankly doesn't matter. He's asexual, a tool of war. You see almost no nods to friendship, emotion, or sexual interest.
The Gears Cogs - Easy target. Yes it's a bunch of muscular dudes, yes girls play almost no role except for a few teary scenes. But as for their sexuality, it's either been gone over, or doesn't matter. Sure Dom has a wife, and Marcus has that Alma thing near the end, but their preference is pointless. They're Bruce Campbell levels of B-Movie awesome. Fairly two dimensional characters shooting things.
Shepard - Now Shepard has overall been shown to be straight, out side of the genderless Asari for females. Granted this is all choice, and there has been no gay male love interest. End of story.
I really think Denby Grace is reaching for an "OMG CONTROVERSY STATEMENT", I apologise for the somewhat smug wall of text.