I'd say waiver on the multi-engine time, but not total time... in the end, nobody has any business carrying commercial traffic with less than an ATP in my humble opinion... Heck, as a CFI, I had over 2000 before my break into the Brazilla.. But fighter guys (there are not many SE fighters left) can get a multi-rating at your local mom and pop flight school and as far as I am concerned demonstrate competence in a simulator on single engine approaches and V1 cuts and when you consider their usually aviators of a higher caliber to begin with, you're probably going to be fine with him as an SIC for the length of time one can expect to be SIC these days.