Is a dirt bike safe to ride on the street?

My daughter's boyfriend just bought his first motorcycle which is a dirt bike. He cannot reach the ground while sitting on the seat. He is planning on getting his motorcycle license ASAP so that he can take passengers... my daughter. He has a long history of motor vehicle violations and actually lost his license on several occasions. That's just an aside. I am mostly concerned about his ability to operate a dirt bike on the street safely with a passenger while having zero to very little experience. I offered to buy the bike from him (more than he paid)so that he could purchase a regular street bike and give him enough money to take a motorcyle safety class (which he feels he doesn't need). No luck. What else can I do?
My daughter is 18 and in college. He is 20 and a HS drop-out.