He's not driving in 6 weeks with a break like that unless they put plates. End of story.
Even with plates I wouldnt risk it, tibia is the main bone of the lower leg (shin bone), another crash could damage it permanently. But without plates and only 6 weeks healing, the pressure applied to the brake pedal would most likely break it again.
Broke my left fibula (the smaller bone behind the tibia) in Feb 2007 and tailored my diet and exercise for a fast recovery, lots of calcium, fiber and vitamin C and still it was tough to walk decently at 6 weeks, qualified for NOPI at 8 weeks though.