Trump doesn't run the states.
This isn't entirely true.
Trump doesn't run the states, but in many cases, a republican governor does. Said governors are pretty much forced to be subservient to Trump and abide by whatever he declares reality to be, at the risk of being voted out for being "too liberal" by their constituencies. If Trump took a harder stance, these governors would be forced to take a harder stance as well; conversely, they aren't realistically able to be much harder on it than Trump is.
Meanwhile, even states run by blue governors likely have large populations of republicans -- within their constituencies, if not within the remainder of their houses of government. These people are also
usually going to be subservient to Trump, and can readily sabotage any efforts made to contain the virus if Trump decrees that such efforts infringe upon their personal liberties. Things like mask mandates or lockdowns only matter if they're actually being enforced, and if the people who would enforce them (i.e. police) skew heavily toward republicans, then the effective leaders of the republican party would have an enormous impact on whether or not they make a difference.
Trump may not
directly run the states, but the reality is that he has indirect methods of holding them hostage regardless. His stance isn't just a symbolic gesture, but something that will impact (and has impacted) control of the virus at all levels of government. If he doesn't want to be held responsible, he should not have sought leadership in an extremely partisan system of government; his doing so is his consent, and cannot be taken back.