If the feds were smart, which is possible, they were just waiting all this time to get most of the leadership alone on the road and outside the wildlife reserve buildings.
My guess - they were running out of time to show results, and this was their best shot at arresting the Bundys.
And color me unsurprised that the Bundys did not go out in a blaze of glory.
Your keyboard is writing checks you might not be able to cash.