Is asking a tank to use his enmity+ buff rude?

[Devaking55]

You should care if it's productive or not though.

Annoying other players by telling them the way you think they should be playing when they aren't interested in your opinion is just going to make the group fall apart.

Now advising someone who is seeking help on how to play their class better is a whole different ball game.

I'm going to point it out, and then advise against it, but if they don't know how to play the group had fallen apart already. Weird that you failed to see that.