15 isn't really a loli, I'd say. But yeah, that needs to be changed. Despite all the perversions going on here, TiTS is a setting where making sure everyone's thoroughly legal is super important - But as long as you adjust the age and keep that in mind for the future, it's not gonna be an issue, I think. I personally think a character who is detached enough from time to have met Victor Steele, and still be able to consider those memories recent could be a really interesting concept to work with - basically he's living off in his own little bubble, completely secluded from the rest of the world and only interacting with people who happen to wander in.
However, working with a character this old is also going to mean you need to be looking at the lore of this universe and figuring out how Vin fits into it. For example, you need to consider how Vin would have met Victor Steele - The planets the PC is exploring during the planet rush are not the same ones that Victor explored, so if he's going to be placed on pretty much any planet other than Tavros or New Texas (neither of which really make sense for this kind of isolated character), you need to figure out how he ended up there after meeting Victor.
Another thing I'd recommend, would honestly be to flesh this character out a bit more before even thinking about writing him as a vendor. Especially with the number of items you seem to be considering, and especially with new items. The general consensus seems to be that new weapons and armor are not something that will be accepted into the game at this point. Maybe start him with two or three items at most, if he absolutely has to be selling things, and focus on stuff that "does something interesting", instead of "does something useful".
