I believe Mango is saying that the Trump staffer is lying when he claims that the cemetery staffer had a mental health issue.

The cemetery staffer was doing his duty, but if the Trump campaign admitted that, they would admit that assaulting him was wrong. So instead, the Trump staffer deflects that criticism by claiming that the cemetery staffer was having a mental health episode.

So rather than blaming issues caused by service, the Trump staffer completely made up issues to justify their behaviour.

It’s highly disrespectful to veterans either way, of course.