>>36305494If he was at least thirty when that was a thing, he would've needed the wherewithal to have known about it. Assuming he stopped trick-or-treating in his prepubescent or teenage years, that'd still leave anywhere between one and a half to two decades of time preceding his discovery of the subculture. I suppose he had a strong affinity for costume parties or something of that like. It could also be further explained if he had kids and enjoyed picking out their costumes for them.
We just don't really know.
