(Remember that? It was in a WSJ article posted here).....also posted here - mad scientist, aryan hate group, "conservative" extremists etc stc. (sarcasm) - I agree with you though, this seems the most plausible. We just need to ask ourselves why the others were put forth - any ideas
The "right wing whack job" hypothesis was peddled by individuals within the FBI who were trying to protect their friends at Planned Parenthood who had been mailing tens of thousands of fake anthrax attack letters.