Like everything else, it depends. There is no "right" answer or hard-and-fast rules. Your husband should absolutely feel able to present his view on any given point, but he should be aware that there may be consequences from doing so. It is difficult for the ptsd sufferer to take constructive criticism without feeling like it is a personal attack. The reaction may be completely out of proportion to the disagreement.
When my wife is having a particularly bad time of it, it is hard for her to maintain even a minimal train of thought, let alone plan a meal, or tomorrow's activities. At times she has an unreasonable fear of situations/people/places/things, and she will do everything within her power to avoid them. This makes a very effective, inpenetrable logic shield.
So, I would advise your husband to pick his battles--if it's not really a big deal, leave it alone. If it is a big deal, go ahead and bring it up. If the symptoms are getting in the way, try again when the spouse is in a better frame of mind.
Good luck.