I know this is late from the date of your initial posting but will share what I know and maybe help others.
It is true that one must be on SS Disability for two years before being eligible for Medicare.
A spouse who is disabled can still be on the working spouses insurance which will be considered the primary insurance and Medicare will be considered secondary.
If a person is receiving Medicare and is also on another policy (not a Supplimental) the Medicare will ALWAYS be considered secondary.

In my case, my employer had Long Term Disability insurance and I was also eligible to continue my employers group insurance under COBRA. This is usually very expensive but luckily our LTD policy subsidized $1200 a month for the COBRA.

Poppa John:
Symptomatic since 1988, diagnosed with Spondylitis, Fibromyalgia, probable IBD March 2013. HLA B27 neg. Sacroillitis, Osteitis, Fibromyalgia
Fused T 2-12, Fused C 5-7, HNP L4-5 with laminectomy/discectomy 2014.