Tom would have been the other extreme of sonny, as sonny was hot headed and always going for the violent methods, Tom would have gone for reason and caution but would have been easily killed by the other families as they were much more ruthless.

For me the battle of sonny and Tom is the battle of extreme reason or Caution against extreme Violence or emotion. Both on there own fail but togahter make hell of a team.

Emotion got Sonny killed and i think extreme Caution would have got Tom killed.