Posted By:
davidcyclebackThe names are known for most people who post under a nicknames. I know who is Leon, PRO9, TBob, etc. At a party, you might introduce yourself as Dr. James E. Smith, call me Jim, then refer to yourself as Jim the rest of the evening. It would come across as strange if you referred to yourself as Dr. James E. Smith each time. Note that, when referring to yourself as Jim, people will have already learned your name.
If the post itself isn't a problem, using a nickname is acceptable. If the post accuses a board member of stealing or trimming, then a full name may be required.
Someone refusing to give his last name to Leon is pretty strange.