Unless it has changed, they have an open enrollment period on becoming Medicare eligible. As I recall, carriers have to offer Plans A and F to under 65. The rates are generally sky high and the commission non-existent. Unless they just have to be in a Med Supp, they are probably better off in a MAPD.
I actually have a case very similar that will be enrolling in MAPD next week, the premiums on med supp for disabled under 65 is unaffordable. If the client is open to it I would defiantly have the take a look at the MAPD plans.