I did like the commentary last night on ESPN, which discussed the reasons why Incognito has been suspended and not simply cut from the team: he's in the final season of his contract, and if he was cut the Dolphins would have to pay out his remaining contract. But since the league has a policy in place for suspended players due to improper activities (with a 4 game unpaid suspension), they can keep him on the suspended list and he forfeits his salary. So it ends up being cheaper for them to just keep him on the team and not pay him.
Different tactic, same result. He's not playing games, AND he's not getting paid. Plus, since he's suspended, no other team would be able to pick him up off waivers, not that any teams would be willing to sign up for the negative PR right now.