Horton was not defenseless, his head should have been up and aware of his surroundings after he made the pass. Horton seem to get hurt when his head hit the ice not from the actual hit which seemed to start from the upper body up to the chin - Rome had barely a second a full lateral speed to change course. Let's also not forget also it all began with Thornton chirping relentlessly at Rome on the bench. A one game suspension would have been acceptable, and it would be a shame that a player who has no history of head hunting or intending to inflict serious injury on opponents could miss an opportunity to celebrate every NHL players dream moment with his teammates. Rome's hit was late.
btw I had no idea Horton has been diagnosed with brain damage.
All said I hope there are no long term effects to Horton.