they would just wait and come back
So what else is a regular user supposed to do?
After this gratuitous offense and waste of time, I as a regular user wouldn't come back. As a spammer/troll I probably would, this looks like a challenge and chance for revenge. Non-automated spamming is done for fun!
Why not something like "Sorry, you are not allowed to post external links yet. You need at least three posts approved by moderators".
--> Too much effort for a spammer.
But someone with a help request will probably just remove the link and accept the waiting time until the post is approved.
No need to be offensive if you don't even know who you deal with.