What's the username? I can check and see if he's been shut down, but if he never even posted before I doubt that, he may well have just got caught in the spam filter if he used an email thats in the spam flag file.
I have not heard back I went ahead and looked at all the new users for the last month. There is no technical reason I can see why one would not be able to post unless it is one of the spammer accounts that was related to mining. If they are still having issues, please let me know to the user so we can look into it further.