They don't say "conservatives" they say "right wing hate groups." The fact is that such groups don't differentiate between Bill Clinton and George W. Bush. To them, they're all "Demo-publicans," just two faces to the same coin.
The FBI has been proven more than once to be incompetent and evil. They are proceeding in the same manner as usual.
Of course there really are real right wing hate groups. Their memberships are so small as to be laughable. I do know that at one time the FBI had more agents investigating the KKK than there were KKK members.