I was under the impression that the president wanted to hear from players who knew someone UNFAIRLY prosecuted. If this person is guilty of the murder then it’s hardly unfair to be imprisoned.
It never hurts to ask... even if you expect to be told no.
When Trump looks at it and says "whoa, I meant people who were railroaded, not killers" the media will say "see, he never meant it when he asked athletes to refer cases to him. Just another Trump lie." Bet on it.