First of all, the road was not blocked. Look at the video there are multiple cars passing right before the other truck pulls up.
And yes it's outside their jurisdiction to enforce state traffic laws. Since they weren't blocked, their issue with her was that she was slowing traffic by blocking 1 lane of a two lane road. That sucks for them, but they could have driven around her and also called the local police to report her for being illegally parked.
Cite the MN law saying you have to exit the vehicle for an LEO bc their definition of LEO doesn't include federal agents:
https://www.revisor.mn.gov/statutes/cite/609.487