The dates and times from exposure to symptoms provide proof. If reopening was causing a huge spike it would have happened sometime in May. Exposure to death is 3-4 weeks. New cases were flat all of May. No death spikes either in May. Hiding ones head in the sand does no good. Spikes do not happen for no reason. The virus passes from person to person, huge numbers of people marching shoulder to shoulder while chanting and screaming are a recipe for new case spikes.
By the way:
NYC's contact tracers have been told not to ask people if they've attended a protest
NYC contact tracers told not to ask if people have attended a protest - Business Insider
I can't imagine why they would do this, well actually I can since the officials and health departments blessed the protests repeatedly.