I think you’re over-parsing their language. A lot of people just naturally use gender neutral language on social media by habit.
Also, advice is often given generally. Although we’re talking about a specific kid, the advice is directed towards any other parent reading the advice as well.
First, I just want to highlight that when considering what is best for a kid, it’s better to consider tradeoffs rather than whether something is “healthy or unhealthy”. It’s possible that it’s unhealthy for your 12 year old to co-sleep with you, but it’s also possible that it’s unhealthy for them to suffer from a feeling of isolation. If so, it may be an appropriate trade-off.
Second, I agree with @Fletcher@lemmy.today. The important thing is to try and address underlying causes, and also make this kind of comfort a short-term practice if possible.
Does your kid have any regular contact with a school counselor that they trust? I think the key question is why they’re doing this now. Is there anything recently that has caused additional stress that is hindering sleep? Could it be natural developmental processes impacting their sleep cycle? Would more physical activity in the afternoon help tire them out so they have an easier time falling asleep? Would a change in eating times or diet help? Would melatonin gummies help?
Also, I think this should be self-evident, but I find it worth saying: I think it’s healthy to have these conversations with the kid. Tell them you’re concerned that co-sleeping is not healthy, but want to make sure they’re comfortable. Ask them if they know why they’ve been having more trouble sleeping lately. Involve them in the process of trying to figure out how to approach this so they learn approaches to mindfully examine and manage their own health.