I'd like to know myself. I find it interesting that no Oathkeepers have been arrested for their participation in the Bundy stand-off with the exception of Delamus who showed up later in the scheme of things.
OK's are not a militia. They are a group of active and retired military and police who promise not to obey orders that are unconstitutional. If they are truly on-mission, their time at a "crisis event" will be spent convincing the cops not to pull the trigger -- which is not generally an 'arrestable' offense. He's kind of asking why a screwdriver isn't behaving like a hammer.
As I recall the OK's showed up and offered material support, specifically comms, and helped to plan for defenses before they were asked to leave.
They have done so more than once, but that is off-mission. You can't expect a huge group to unabashedly get behind off-mission activity. I think it's enough that the wide majority of the org tolerates it, given it's off mission status.
I'm well aware they they are not a militia. However, many militia have been arrested in support for Bundy stand-off for doing nothing more than what the O.K.'s provided.