I know JG has been criticized for frivolous trust ratings, and deservedly so in some cases, but this ain't it. It's a neutral. Anybody can post a neutral for any reason, and using neutrals to comment on post quality is fine IMO.

Having said that, a sig campaign manager can interpret neutrals (or negatives/positives as well) any way they see fit, and a user can choose to join or not to join a sig campaign if they like/dislike that, so it's a non-issue either way. But it would be better to have such rules (e.g. "no neutral ratings from DT members") posted publicly instead of being applied ad hoc. Informed decisions FTW.