If today's standards indicate that someone's past behavior was dick-ish, then the fact that the standards have shifted does NOT imply that the past behavior was somehow "just fine" because... We didn't expect better of each other?
By that logic, abusive racist parentage back in the 50's is unassailable acceptable, because as you say - we're judging it by today's standards.
Acceptability in the past is no indication of an actions morality or ethical... ness.
... Words are hard.
Besides, what's with this tendency to escalate way beyond the topic at hand? We're talking about professional pranks and suddenly...racism?
So no, this apparently was not "expected" because otherwise they would also just have had a chuckle and wouldn't have reacted like that. And regardless of whether that means the sales person was in the wrong job or not, the fact that that person was in trouble, and OP did nothing to help, means that OP was being a jerk.
Maybe HN is finally maturing.