You guys have to train with him. She has to live with him. Sounds like sensei has a problem. Talk to her some more. Talk to him. Put it flat out that husband is killing her dojo by holding everybody, himself, her, other students, back. Find out if he's killing more than that. If she cannot get a handle on this problem, hand sensei a card for a marriage counselor and go train elsewhere.
How does rank manifest itself in your dojo? This guy may be holding your ranks hostage, but he really cannot be holding your aikido hostage. Anything stopping you from just being a whole lot better than he is and just doing your best aikido? What happens when you go to a seminar (preferably in your dojo's association, if you have one) and other folk see that you are being sandbagged?
Damn Krystal! Direct, Honest and willing to enter into the conflict! Just like a good irimi....Good advice.