Well it's true Trump isn't directly responsible for local law enforcement practices.
However. Trump's response opens up a big can of worms:
--He sent unmarked feds to Portland, uninvited, when the protests were actually dwindling and that exacerbated the protests
--He could order the DOJ to look closely into local law enforcement practices like the Obama Administration did in Ferguson, Baltimore, and elsewhere after police shootings, but he just hasn't
--His staged photo op with the Bible at that church required tear-gassing protestors and his public statements on George Floyd and other shootings haven't helped unify the country at all, only led to further division. He just doesn't speak the language of sympathy and healing very well, quite unlike Biden.
Systemic racism in America and bad cops can't all be traced back to Trump. They've been with us for decades.
And Democratic cities certainly aren't utopias, yet Trump as the President is where the buck stops according to Truman's famous quote.
Trump is the figurehead of an entire "Blue Lives Matter" worldview that backs cops 100% and doesn't support meaningful reform which is what the protestors (non-violent and violent) want and will continue protesting until they get.
Changing stuff is hard but we have to try.