Ok first of all I think you mean Horton, not Thornton, which by the way makes it sound like you're the typical American hockey fan who only starts paying attention when (insert NBA team here) is knocked out of the playoffs and isn't paying enough attention to know the names of even the star players, but I'll assume it was a typo.
Second reason you don't know what you're talking about is you called it a blindside hit. This is why I hate the NHL introducing rules with names like that, because people who don't know or care enough to educate themselves end up making ridiculous comments. It is decidedly NOT a blindside hit, and this has been made clear over and over again, including by Murphy when he handed out that suspension. A blindside hit has to do with the direction the players are travelling, not the direction the guy getting hit is looking. You cannot throw a north-south hit and have it be "blindside". We've talked this to death and apparently still people don't get it, which again leads me to the conclusion they just don't care enough to pay attention.
Next, I should point out that the number of strides does not have any relevance to anything whatsoever. It is the time elapsed that matters. You get .5 seconds, basically, to hit a guy. This was slightly longer than that, therefore it was illegal. I have seen later hits that cause injury let go plenty of times in my time watching hockey, particularly in the playoffs, but apparently the standards have changed and that's all well and good, though 4 games is still very surprising.
Next, you really, REALLY have no clue what you're talking about when it comes to Rome. He is not a goon, he is not out there for "one reason", his purpose is to play stay at home D, not injure people. I can't even remember a big hit he even threw in the regular season and he doesn't fight or get into scrums on a regular basis. You assume because a guy is a 3rd pairing d-man his only purpose is to hurt people, and again, this just demonstrates your willingness to make ignorant comments about hockey and this series. That is not the sort of player he is. There are lots of lower-line guys who are just there to rough it up, sure, but he isn't one of them - the closest we have to that is Tanner Glass, or Rick Rypien if he were playing.
Now, I may be biased, but everything I have just said is unequivocally the case.