I've always believed in shaking hands as being the foundation stone that signifies the end of a sporting contest. Something symbolic that states that the game matters, but after all, it's only a game. This, however, cannot be an immutable rule.
If Mourinho had said the disrespectful things about me that he had previously said about Pellegrini and then displayed the same degree of disregard for the rules of sporting etiquette by invading my territory in such a truculent fashion, as he did in Sunday, then I would have rather died than shake his hand immediately afterwards, and furthermore I would have said to anyone who thought that displayed a lack of "class" that, quite frankly, they can go fuck themselves.