I am on the road and don't have the time to research the question, but I believe there is employment law separate from SSCRA protecting jobs. They have to get a comparable job at the same wage.
As to applicability of SSCRA if the employer continues to pay them plus they get active duty pay and benefits, it applies. Regardless of the income amounts, SSCRA protection is triggered if they ask for it. To terminate it early, you have to challenge it in court.
Opinions stated are not necessarily that of my employer.