Just ignore them, and if they still, say something like: Well, thanks for the messages, I will vote normal
I should play more games with you :PI hugely agree with you... I hate the people who spam OP in chat and I want to do hardcore but I don't do it just not to be mean :o
I don't believe that's how it works as I played a game with Mrtokay before where he forgot to vote and an emerald rank voted op and triple health. Right before the game started the emerald rank left and it ended up being normal items and normal healthBut I don't see a point in blocking it. If people spam it, just vote hardcore and triple health, then leave.
That work if you have the 5zig mod you can see who can voteThe reason they aren't filtered is because you wouldn't be able to say "peOPle" or "pOP" and many other commonly used words. Many have made the suggestion for anonymous voting and name colors which I think will work the best for this