Of those heavyweights, I think he would beat Couture, Hardonk, Werdum, and possibily Sylvia, maybe Gonzaga if Silva can get it past the first round; as for the rest, no. Just because he fought at 205 doesn't mean he can fight heavyweights. Good god, the size differential is enough to decide the fight.
To quote Mr. Irvin, "there's weight classes for a reason."
You just listed 5 of the top Heavyweights in the world and said they would lose to Silva, and then said he can't fight heavyweights
Brock has nearly 100 pounds on him, which is clearly an advantage, but he would have to bullrush it to the ground and just lay on him.