The whole idea is just weird - just why?!
One think I noticed about this is how frequently these events started to appear after the first few. This seems to be common with programming at places like libraries and museums these days, anything that gets a response in terms of bringing people in is picked up and multiplied like lightening.
The answer to your question might be just that some person thought it would be a good idea, or someone offered to do it, and it just hits all the "right on" buttons of the moment. Diversity, LBGT, culture, Drag Race and drag kids, whatever. And for a lot of people they don't differentiate drag queens from trans and they think they are identities rather than acts.
But I don't see how it really makes sense even if someone thinks drag is fine, or you look at the very best, smartest, well done drag acts.
It's a bit like they ask Peter Dinklage to come in to read a story to promote diversity, but they get him to dress up as and inhabit the character of Tyrion Lannister, and advertise it as Tyrion Lannister coming to the library to read to pre-schoolers. And the preschoolers of course are all like, who is this guy, why is he wearing those weird clothes and talking like that? Because they aren't allowed to watch Game of Thrones and they can't read.