Bill,
You could tell 2tf about the Copper Membership and then point a link to that thread and tell him that buying it will allow him to post images without restrictions like a normal member. That how you could manage this newbie from PM spam and also solve their problem at the same time. If they are presistent then you can add them to ignore list and delete all PMs without any further response.

Giving a tag here whether neutral or negative in my opinion is less important than the decisive solution which I speak of. A tag is an overkill in this case because a generic shitposter is also not a valid warrant for the same.

I dont understand why you all are getting so trigger happy with tagging people for every case. Sometimes the logical method also works. Obviously if the person repeats offenses then a neutral tag would be appropriate.