From Rob Porter's Wikipedia listing I linked in an above post:
DOMESTIC ABUSE ALLEGATIONS
Both of Porter's ex-wives accused him of physical and emotional abuse.[14] He denied the allegations and resigned from his staff secretary post after they became public.[23] Willoughby sought and received a three-day emergency protective order against him in June 2010.[24] In February 2018, she told the Daily Mail, "I don't want to be married to him. I would not recommend anyone to date him or marry him. But I definitely want him in the White House and the position he is in. I think his integrity and ability to do his job is impeccable."[25]
If Porter's abused ex wife thought Porter was very competent and shouldn't lose his White House job over abuse, then I don't think Trump did anything wrong in simply saying he was a good employee and regretted circumstances forced him to leave.
