If you are well aware of what a charge is, then you know there is nothing in the rule or definition of a charge that says anything about 3 strides, I'm not sure where you are getting that. For fun, let's assume there was some rule about 3 strides, could you point out where in the video Rome took 3 strides to make the hit?
I'm well aware of what a charge is and I think they got the call wrong - It sure looked to me like he took more than 3 strides, also, Horton wasn't "watching his pass", he was checking to make sure he was onside and the hit was way later than "just a second" -
Maybe I'm thinking about a different hit.....the hit I saw has Rome skating backwards as Horton is carrying the puck through the middle of the ice in the neutral zone. Horton passes the puck and then Rome comes to a stop at the blue line to lay the hit on Horton. By my count, there were approximately ZERO strides.
Regarding checking to make sure he was onside....I'm sorry, but I have to call BS on that. He passed the puck ahead to a player receiving it just before the blue line. That player was a few strides ahead of him....there is no possible way he could have ever gone offside, so if he is checking to make sure he stays onside, he doesn't belong in the game of hockey, let alone playing at the NHL level.
Back to the actual suspension....4 games...wow, that surprised me. You have to believe that if it wasn't a star player from the Bruins that got hurt or if it was as star player from the Canucks making the hit, the suspension would have been less.