Can an individual (non-miner/or miner dealing with coins not mined) in the USA, buy & sell bitcoins on an exchange without needing to register with FinCEN? I still haven't found a clear answer with this question.
Per FinCEN guidance I already answered. If it is done infrequently and not for profit then that exemption applies otherwise registration is required for ALL exchangers.
Now is FinCEN going to send storm troopers to break down the door of every unregistered Jalapneo owner? No. That is the problem with poorly written guidance. If the guidance as written won't be enforced then what will be enforced (i.e what is the "defacto line")? Who knows.