I don's see how ranked choice would be unconstitutional. Each state has the power to elect its officials in accordance with its state constitution and statutes.
The way I was reading it, though, is the algorithm is actually assigning the votes based on some weird code. If you had ballots where people were actually putting down "I like this guy first, this woman is my second pick, and as a last resort I'll live with this loser here", I could see that as an option. Weird, but ok, if that's what you want in your state. But to have the computer assign votes to someone else ... I don't know about that.
KC