[Windflier]

Barefoot guy with gun jumps in your truck and says "drive!" Not sure how I would react.

Well the report does say that Willeford briefed Johnnie on what had just happened, before they began the pursuit. I suppose it all clicked for Johnnie, and he got right on it.

[Paladin2]

Johnnie apparently witnessed part of the lead slinging, knew who was the chaser and knew that that guy was not pointing the gun at him while asking him to drive.