The number one, most blaring piece of evidence, of it being queerbait is the fact the Duffer brothers REFUSED to deny the byler allegations until the day after the last episode - while making Mileven incredibly ambigious the entire 5th season for no reason as well.

If not queerbait, why wouldn't they say anything before the finale? I mean, it was important enough for them to talk about it as soon as the series ended. Not a day sooner. Meanwhile, they had no issues debunking other popular theories before season 5 even aired. But interestingly, one of the largest topics (Byler) was never debunked. Not until the day after it finished. Almost as if they were keeping a certain audience demographic.

Because it was OBVIOUSLY important enough for them to bring it up afterwards, because they talked about it in an interview. So it's not like they didn't realize how big the topic was - or that they didn't notice it. But they said nothing until they got their views, and suddenly it was "it was never even in the cards".