They can pay for Debian support! (I’m not 100% sure who they should go to, but e.g. Freexian are doing Extended LTS for Debian [1], so I suppose they could do a regular support contract as well?)
But by definition it wasn't a bad choice (or a mistake) if it seemed like the right choice given the information available at the time. Unless you have some sort of crystal ball the rest of us don't.