I know that Koren's salary goes against the cap regardless, but I always thought the player had to receive some type of settlement. In other words, I always thought a player could not be cut due to injury. That's the part I was curious about.
You're right, the team can't flat out cut a player due to injury. They have to reach an injury settlement with that player, generally a sum of money in exchange for agreeing to be released. In the case of Koren Robinson, he's not technically injured, even though rumors have it that his knees are bad. But that by itself wouldn't be enough to prevent the Packers from being able to releasing him.