I agree with a lot of what you said, that thread rather got out of hand and people, including myself, were commenting on it before further details of the case had been made clear.
I do think personal responsibility and taking responsibility for your actions is a major part of barebacking, and that the vast majority of 15 year olds are able to take on that responsibility, regardless of whether the law says it is 14, 16, 18, 21 or illegal. That really comes down to age of consent, which is just another societal construct and doesn't really make a whole lot of sense, although I personally would never sleep with an under 16, partly because of the law but also because I prefer guys in their 20s and 30s.
On the point of stealthing, I would say that there's a big difference between just not mentioning your status and lying about your status. Not mentioning is something that occurs between both partners in a sexual act, the negative guy should ask just as much as the positive guy should, if neither do, there is an implicit agreement that it's not important. However, if one or the other asks, then an honest answer should be expected from both, if not, that's a serious betrayal of trust.
Do I think HIV-transmission is attempted murder? No, do I think not mentioning your status should be punishable? No, do I think lying about your status in order to attempt to spread HIV is wrong? Yes, you then reach a point of what sort of punishment, and I run into serious difficulties here, if transmission doesn't occur, I struggle to see any provable criminal intent, if it does occur, then I guess it would be some sort of assault charge, an attempted murder charge in a Western country is just ridiculous.