and how do you know that?

you feel like a victim because society is indeed oppressive towards LGBTQ minorities, but if you see yourself as a victim all the time you'll just end up depressed and miserable.

no, Steam is not being biased against minorities, intentionally or otherwise, they're just not. This feature was in beta for a long time and for most of the beta anybody could join any family from any country. The choice to make it more restricted wasn't to fuck up people who don't live with their families - it was to prevent the abuse of the feature that must've come to light during the beta.

Steam wanted to improve their family share, and the did, greatly in fact. But they had to include limitations to prevent cases where someone gets financially abused online, or someone joins a stranger's family and then gets kicked out immediately and needs to wait 6 months join any other family, or someone joins a game hoarder's family and then never buys a game again.

That limitation can still be worked around the good old way - by logging into another person's machine and joining their family that way, but for that you need to trust the other person to not fuck up your account - and that's enough to discourage most of the extreme cases. They're just not going to beam that information to the public as that'd defeat the point of establishing that limitation in the first place, and even encourage people to trust random strangers that could have malicious intent.

Maybe, it still doesn't mean the intent is to hurt non-cis people and you can't expect them to make an exception for people they can't prove are part of a certain minority and you can't expect them to make the thing free-for-all either.