I think that old school guy can be described as a guy that follow the rules,keep his mouth shut and done his time in jail.
Yes this are only world but people like Al Trucchio that made 8 y but risk more as a Gambino capo given that his father get life or jerry bruno that get life at 43y and is only sn associate or the other mobster that even was young and with family didnt flipping and serve or are serving harsh sentences like Nicodemo in philly.
Or John Pappa a colombo associate that was serving life for 4 murders and for sure if he would flipped (in 1999 the feds are serching rats after wild cutolo death) he would get few years.