Yes, it's really unfortunate when I see people of a given oppressed group start attacking an ally simply because the person hasn't kept up to date on the latest preferred words. I know there is an angry subsegment of people that feel that everyone should spend all their time keeping completely up-to-date on the latest terminology, but it's a really unrealistic and damaging expectation.
There are often people who want to do the right thing and are simply out of date, or not well enough informed. These sorts of people can and should be educated as they generally want to help. When they get canceled for minor transgressions it's not constructive.