Interesting argument... My contract makes no mention of 'single pilot' just mentions that 'I must be medically fit to fly' and that I hold a JAA commercial pilots licence which is a legal argument that I have yet to have. My contract does state that it is terminated at age 60 though...
Personally I would take tha actuarial reduction and retire gracefully... flogging around on a pitch black night at 500ft with minimal viz at age 60 loses some of its appeal.