I've been hearing the term in IRC and discords for about a year or more already.

I get that it can seem childish but when you compare that to the indolent people who are demanding AI, it cancels out.

It is a thing, i've been hearing it for at least 6 months. There's a lot of people who really hate AI and want nothing to do with it.

You can find the answers to both of your questions on Wikipedia: https://en.wikipedia.org/wiki/Clanker