Our hotfix for this issue is now live. The benefit of a Zul’Gurub class enchant is canceled if:

The player is not the correct class to use the enchant.

The player is not level 60.

The item itself will not be destroyed, and the enchant text will still appear on it. If they have one, players can replace the nonfunctional enchantment with another one.

We have have a hotfix coming soon that will prevent this sort of trade from being operable in the first place.