I don't think he's actually trying to get the black vote with this one.
Honestly, I think he's trying to calm down the black vote to a point where enough of them will stay home and not vote for Biden.
Plus the virtue signalling can also win over some of the more moderate-leaning white Karens and Boomers who don't want to be victimized by rioting but won't vote for Trump if he goes all Justice Hawthorne on BLM right now.
At the risk of sounding like a "4D Chess" Q tard, it's all about optics so he can win 2020.
Again, not everyone is a raving traditionalist lunatic who wishes real life was like Arthur Miller's The Crucible or a game of Crusader Kings II. Trump isn't trying to appeal to the traditionalists because they won't vote for Biden anyway. He's trying to win over the "normie" vote
Going full Justice Hawthorne on BLM right now just gives the Dems more ammunition to use against him and energize the black voters to actively go for Biden instead of sitting things out.
Trump making a peace offer while the Democrat-run cities and states continue to be hammered by BLM rioters gives him more ammunition, since he can just pin the blame on the Democrat state leaders in his campaign ads.
The fact that Trump's son-in-law belongs to the same tribe as Jeff Goldblum, King David, and Jesus of Nazareth is mostly irrelevant in this.