What is silly is that it was obvious that lynch must have known before he left the ground that he was going to be cut off and had no chance of taking a mark (contested or uncontested). The fact he clearly still followed through with the contact (knee or not) was clearly careless, the contact forcefull and dangerous. It deserved a week at least to show that once you are out of a contest there is no room for people to hurt an opposition player out of frustration
By the time he was "out of the contest" he was "already in the air". He would have "needed air brakes" to avoid that collision.