I didn't get the details but teachers who sing folk songs can approach them with knowledge and information that is useful to an audience and may be able to communicate with kids better than the standard folkie.

The question I would have is what was the motivation here? To actually educate, to patronize, to do an ego number? This wasn't clear in the post.

I have known some teachers who were very knowledgeable about folk music and could
communicate some important values to an audience about history, the nature of the music,
and present a credible performance.

The thing to avoid is snobbery. There is no one way to do something. The post needs
to specifically articulate what was offensive and not generalize with reaction.