I think it is not only safe but correct to say that George Floyd's murder was unjust, detestable, and should have never happened. The officer who murdered him should be held accountable for his actions.

That being said, violence never brought about any change in the United States in recent history. It's rather evident that nonviolent protests are not only more effective than violent ones, but also result in a higher turnout and have a lower risk associated with them. No one looks back at the 1992 Los Angeles riots and believes that to be a turning point for Black Americans. If anything, it brought more harm than good to the community.

There is no philosophical justification, either, especially in a democracy (or to be more technical, a Constitutionally Representative Republic in our case). Protests work in countries with dictatorial regimes because dictators will not bow to the voices of minority groups; in the U.S., with relation to this scenario, violent protesting is the moral equivalent of having someone in your household murdered then throwing a brick at your neighbor's window. It's frustrating because there is no prior involvement or connection from these institutions, like local businesses, to said events, yet these are the places subsequently robbed and burnt. It reminds me when I saw a video of a Black business owner in the 92' riots whose business was torn down and robbed.

Often people cite how Martin Luther King Jr. said that a riot is the language of the unheard, but King never participated in a violent protest, never advocated for violence, and in the same interview after making that statement, he said his hope would be that protests remained nonviolent and that they should be "militant and determined" (source).

What's truly unfortunate about this situation is that there are people using nonviolent protest as a mechanism to redress genuine grievances, things like racial equity and equality, but nonviolent protesters muddy the water for these people, ultimately harming the cause.