Imo the fact that Michael changed his mind and Carly destroyed the evidence should matter to Sonny and that part could and should be forgiven by Sonny....Michael was upset and was acting out of anger. But not coming clean right away once he changed his mind and lying to him for the following year is probably a different story. Carly/Dex/Michael lying for a year in order to babysit him is more unforgivable to Sonny and I get that.
As for Sonny calling off a hit, to me it matters that he decided against it. He was acting in anger and frustration but thought better of it....much like Michael, but for different reasons of course.
