It's waaay worse than that. My understanding of the point of incommensurability is not the obvious morality is different from science but it goes back to Kuhn in the Structure of Scientific Revolutions where he argues scientists speaking literally the same words with different paradigms of understanding that science will suffer from the inability to communicate effectively because the differing paradigms lead to different meanings and ways of interpretation.
There's 'science', 'morality', etc. Not all decision are scientific, even if they require scientific knowledge as a factor. Here he aligns with Focualt when discussing power and the urge to use science, or Hayekian scientism, to say there is one true way and the decision should be X.