My point is that there is definitely still some wiggle room in whether states can require electors to vote in a particular way. I'm sure that state laws requiring electors to vote for the national popular vote winner will be challenged in court AND ignored by at least some Republican electors whatever the courts rule.
It's far simpler than that. Each state has a slate of electors for each candidate. If Ohio laws is changed to say that the slate of candidates for the winner of the national popular vote is the slate that is allowed to cast Ohio's votes then what is to prevent them?