Jack Tramiel didn't ruin Commodore. He ruined Atari.
But that came later...when he first took the company from Warner Bros...he really got the company moving for a few years. Unfortunately in later years, it was mostly a series of mistakes.
I remember reading stock holder reports that said such gloomy things as 'we cannot sell the units at any price point' and 'we fundamentally don't understand the business we are in'....talking about the jaguar...which completely failed to do 3d well, in a time when that was a requirement.
anyway...still, cannot deny he was there doing great work for a while.
No reason to believe the Tramiel family would have kept Commodore going in later years, though.