Truth is very important to someone who struggles with PTSD. When something bad happens, at the very least, as bad as it is "truth" about it brings an important comfort and sense of control whereas when the truth is not stated it upsets the mind in that a problem cannot be solved without understanding how the problem happened and how steps can be taken towards prevention.

What you described can be especially triggering when one had a childhood were they did not feel safe, dealt with "untruths about threats" where the child's ability to problem solve was at it's most vulnerable. And the one place that tends to get stored is in the emotional area of the brain. We never forget how something or someone we experience in our lives makes us "feel". We are emotional beings and it's been a significant part of our survival as a species.