Mate, everyone above has a very valid point. I think your initial statement is important though, you said it was against your principles. Everybody here has different principles, its what makes them real people.
If this is against your priniciples then there shouldn't be any question whats right for you, why change your principles to appease someone on the offchance they might employ you later. That same person might well ask you to do something unsafe in an aircraft (everything comes back to money), will you change your principles then; and get pushed/coerced into a bad spot.
If they are a worthwhile employer/team, they will understand your concerns and maybe sort out the insurance issues, if they are not they will throw out the 'well we'll find someone else'. In which case I'd say sod them.
TW