Presentism fallacy

The logical flaw here is that your argument implies that "changes in social culture and attitudes" either occur separately or indifferently from the "emergence of new information", when in fact it can be easily shown that the two are necessarily coeval.

I think this may qualify as an ambiguity fallacy as it is a phrase and not based upon a single misinterpreted word. (Equivocation Fallacy )

Changes in social culture and attitudes occur with the introduction of new ideas and information.

Therefore, any society or culture that is immune to new ideas or new information will find social change to be extremely difficult. 

For instance,  The Constitution originally defined African Americans as only 3/5 of a person. Obviously, with the introduction of new information (over some four hundred years), we realize this to be a preposterous claim. 

The other flaw I see in the OP is that it assumes that just because some people found a morally repugnant and obsolete idea to be funny it somehow excuses it from being racist or discriminatory. (It's possible to be both). Don Rickles could be both hysterically funny and shockingly racist at times, but with new information and changes in attitude, his comedy act drew more and more criticism and eventually grew out of favor. Minstrel singers were once considered to be a high note of musical and cultural entertainment, but as new information and ideas poured in we realized that it was at the expense of reducing, stereotyping, and dehumanizing whole groups of ethnic people.

It doesn't sound like that's quite what I mean. I was referring to changes in social culture and attitudes, not emergence of new information

It is basically the same. Person X who made a decision to create a sitcom in the past that would be sexist today, is judged based on today's social norms (information person X did not have in the past). The changed social norms or attitudes would be the the same as new information, for the purpose of this fallacy. The flaw in reasoning is the same.

To echo what Dr Bo said, you've basically got two forms of the historian’s fallacy - type 1 and type 2.

Type 1 is when you make factual claims using information the person did not have at the time.

Type 2 is when one reads present day morals into older time periods, without regard for the norms they held back then.

Jo:  That statue of Robert E Lee should be removed in Richmond because he waged a civil war in defense of pro- slavery states. The Richmond citizens that want to keep it should be ashamed for thinking Lee is a hero.

Kai: I'm shocked, Jo! You committed the historian's fallacy!

Jo:  Did not! Leaving the statue is a present practice that violates present values. I'm not judging past behavior, but the behavior of the current powers that be that want to continue honoring REL as a hero.

Well?

No fallacies, just looks like a heated debate. 

I agree with you, Rationalissimus of the Elenchus, of course. I posted the conversation only because many people (and even some cable news networks and podcasts) agree with "Kai" with respect to Confederate statues, buildings named after slave owners (even Thomas Jefferson), etc. You know..., the "cancel" thing. AAARGH!