Are they really though? People are generally considered heterosexual by default if not stated otherwise, and most TV shows don't reveal this aspect for most of their characters or performers.
From context, I don't think they mean the phrase literally, it's really just a shibboleth of the progressive political movement in the US, with connotations of a person going public about a facet of themselves they had previously kept private due to fear of judgement from others or similar negative repercussions.
As well as still being used as an offensive slur against gay people and thus not really an appropriate term to use in these sorts of discussions, 'queer' is so ill-defined that it could include pretty much anyone if they feel like it, regardless of actual sexual orientation.
For example, 'demisexual' people are included in this categorization, even though all it means is that a person prefers to form an emotional bond with their partner before engaging in sexual activity. Not only is there nothing particularly unusual about that, this includes people who are heterosexual. Who are not a marginalized sexuality by any means.