Biden really needs to mostly stay quiet and not attract negative press over the issue then simply let Trump keep going with his press conferences and comments which just might contribute to him being a one-term President when things come to a head in the November 2020 Presidential elections.
If Trump can work his way around his words and race-relations improve along with confidence in the Police and the legal institutions across the USA then Trump just might be back for a second term and it might signal the end of the political career of Biden.
Trump is the president so he's expected to actually do something to resolve the crisis. Biden only needs to avoid saying something stupid.
History shows that both these things are pretty much impossible for those two geezers so I'm guessing there will be no significant advantage for either one of them.
Common sense can't be applied in this day. Most of the things that Biden said throughout his campaign should've sunk it -- based on the weird things that he's said. And the same can be said for Trumps 2016 election and the upcoming 2020 one.
We literally broke the common sense theme this year when Biden - who will be the Democratic nominee, lost both Iowa and NH.
So yeah, not too much common sense and precedent can be applied.