I ride a motorcycle, probably one of the fasted street legal production bikes made a ZX14. That little piece of info sets it up for I have a small clue regarding I know what I am doing. I only say small because on a motorcycle you can never be fully prepared or fully have your act together, you can only minimize your risks and have a plan if the sh*t hits the fan.
I learned how to ride back in 93 from a MSF course I took so I could learn to ride AND so I could get a bike on the Naval base I was stationed at. Since then I have taken several more MSF courses to get friends involved in motorcycling and to continuously refresh my skills. So I am VERY glad your husband took that course.
Now on to your question, one of the biggest things I remember or have seen in the classes I have take is dirt bike riders crossing over to street. While the concept is the same the application is not quite the same. Much bigger bikes with more power and more weight. Additionally, running in the superbike world a huge recommendation is to get a small bike and learn how to flog the crap out of it, this will make you a more proficient rider. So my suggestion is get a used, maybe smaller bike (a Suzuki GS500 or 1200 can be had cheap) that your husband can flog on. Get his proficiency up and get used to riding a street bike. Then take the new bike back out and enjoy it.
So yes I think the learning curve will be overcome and all will be well.
I am glad he is ok and I can relate to him being bummed about wrecking it. Been there done that.
Cheers
K