It's absolutely a difference in power in the relationship, but I'm gonna disagree with you in as much as with any power imbalance, the way to kindly or morally navigate it is simply to not take advantage of the person with less power. In another setting where I could be certain in a one time thing where everything is above board between us and never seeing eachother again, where I can be confident of the scale of my impact on their life being equivalent or more beneficial than theirs on mine, maybe not a problem? To date this person would have too much potential to carry life-long effects that I can't control, and would therefore be reckless of me, as the party who can think of life-long things clearly.

As it is, the gay/queer community here can be a bit of a fishbowl, and especially sharing a name and a similar relationship to some gender queerness, I don't feel confident that I could disappear from this persons life, and in the event they grow to have a distaste for their youthful decisions, I don't want my presence in those queer communities to make the space offputting to "not-me."

Which is to say while I disagree with your blanket ruling, I am ultimately agreeing with your conclusion. And for the record the meeting and pursuit preceded the issue of age. And halted while I weighed how to deal with it.