@MartinSleziak there were unforseen objections. I'm (still) for grad-curl-div, but the opinion on the mod team is divided, which is why I haven't acted.
because tag merge is irreversible I tend to wait for consensus before doing major synonym work
@AlexanderGruber I will point out that it is true that merge is irreversible, but synonyms (without merging) can be changed at any time.
But I am glad to here that this is at least discussed by the moderators. (I guess it is implied by the message saying: the opinion on the mod team is divided".)
Concerning merging vs. only synonym, I guess in this case synonym without merging might be a better option (even after some consensus is reached). Simply because several possible option were discussed and in the future, the mods (or the community) might decide that a different target might be better.
I suppose that by those unforeseen objections you mean something which was discussed in a mod-only room - not somewhere public (like meta or a public chatroom)...?