If you lay-off someone who is on disability do you have to lay-off everyone on disability?
What this means is that the management looks at the work that will need to be done in order to run the company efficiently and effectively. Then, they eliminate jobs by redistributing tasks/combining jobs or determining that certain work is "nice to have" versus "necessary" to the company operations. So, the management cuts jobs--not the people in the jobs--although the effect to individuals feels like the latter, versus the former. Your job must have been one that the company management felt they could accomplish through other means.
The common denominator in the jobs eliminated should be that the work can be accomplished through redistribution or that the work need not be done going forward, not the ability or disability of people in the job(s).