According to Roberts Rules of Poker:

The following actions are improper, and grounds for warning, suspending, or barring a violator:

Revealing the contents of a live hand in a multihanded pot before the betting is complete. Revealing
the contents of a folded hand before the betting is complete. Do not divulge the contents of a hand
during a deal even to someone not in the pot, so you do not leave any possibility of the information
being transmitted to an active player.


Not cool for sure but nothing about calling a hand dead.