TRACON Operations Supervisor reported being instructed under duress to operate against VFR Tower contingency plan with having 2 operational controllers for a 5 hour period.

Narrative

We normally have a complement of 5 controllers for our evening shift. Due to some FMLA and sick leave hits were reduced to 2 controllers from the time of XA:30-XL:30; so about 5 hours. We normally would go to a VFR Tower configuration and give up our airspace to ZZZ Center. As the OS (Operations Supervisor) I told my ATM (Air Traffic Manager) of our plan after discussing it with the affected controllers. He told me to tell them that they would TRACAB it for the 5 hours. His plan was to give up the airspace and take it back periodically so breaks could be accomplished. I told him it was impractical to have just 2 controllers to each work a position almost continuously for the 5 hours. I told him that the amount of extra coordinations with ZZZ/ZZZ1/ZZZ2 to open/reopen the airspace multiple times would be a big complication. I told him that I and the affected controllers deemed this an unsafe operation. We have a VFR contingency plan for this exact scenario which we have used before. I asked for his request in writing due to me feeling so uncomfortable with it. He ordered me to tell the controllers to TRACAB for the rest of the night or he would get me for insubordination. I did what he requested. I believe there was no margin for safety in this situation. If one controller was working a Tower/Radar emergency or incident when the other controller was busy working the other position then they had no options. I feel like my authority was completely undermined and my judgement belittled by the ATM. Recommendation: As the OS I believe we should have went to a VFR configuration due to only having 2 controllers for most of the night. We should follow the procedures set in our VFR Tower contingency plan.