We need a word for a Midas touch except instead of gold everything turns to feces.

Absolutely, not to say "You are right!" :) The items touched by Midas were if nothing else, shiny and gold after all is a precious metal preserving its material properties for a long time...Whereas the stuff produced by LLMs...yes, quite resembles the key properties of feces, come to think of it. It is a simple meshup of whatever was digested over a timespan, it stinks, and it does not require special skills - anyone can produce one!

Montezuma's touch

That’s the Mierdes Touch.

We just need people capable of understanding it's a curse.

.. and maybe to ignore whoever can't.