That's not the problem.
The problem is that, to coordinate, count, and certify a "national popular vote", the national government is going to have to be given control over voting in the States.
Therefore, the people in charge will be given control over the process to replace them.
Something to consider:
In 2016, Trump recieved 3.0 million votes in CA while Clinton recieved 5.6 million in that state. In OH, Trump recieved 2.8 million votes to Clinton’s 2.3 million votes.
What is striking is that, under this compact, OH would still award its votes according to the CA vote total even if ALL of Clinton’s 2.3 million votes went to Trump given him a unanimous victory in OH.
Can people in OH be that stupid?