You said they "should have the ability to choose whatever programming language they prefer". I have good news for you.

You have correctly identified that the developers are responsible for their own decisions. They are, you will be very relieved to hear, quite free to make as many poor decisions as they will. Nobody is going to force them to stop.

Other people are more than capable of identifying that those decisions are mistakes. Now, that could be argued with, you could explain how it's not a mistake.

But you haven't. You just said they should be allowed to do it, but nobody was arguing that they needed to be stopped, just that it was a bad decision.

Edit: this person didn't actually say that first quote, but the line of argument proceeded from there, and they did nothing to distance themselves from that point.