The constant overreach and reversals ARE the strategy - it's what the only way to find out what will and will not trigger a backlash, and it's what Trump has done all his life. It's not vacillating, it's making other people do the work to figure out what and what not is worth fighting for.
The only reason why this works is because, no matter the outcome, Trump will be fine and never face any consequences for running other people's lives.
There is a deeper lesson here, and it is that law enforcement and prosecutors need to focus first and foremost on the harm done by the most powerful, not those with the least amount of power.