In my opinion, there's a lot wrong that happened here, but very little of it had to do with the hit.
1) Hit seems fairly clean to me. I wouldn't wish what happened to Toews on anyone, but it's hockey. There is always the potential for nasty stuff to happen. Seidenberg did what he could. The boarding penalty is right. The supplementary discipline should be nil. It's not malicious. Seidenberg has no pattern of this kind of stuff, and probably doesn't intend to start such a pattern.
2) Both coaches were terrible. Clode, shut up. This isn't the time for "keep your head up". What's next, telling cancer patients that they shouldn't have smoked so much? And as for Quenneville - I don't care if it's an early regular season game, or the 7th game of the Stanley Cup Finals. You don't ever put a player in when he takes a hit like that. Ever. You give him the 15 minute test in the "quiet room". This isn't a finger sprain that you can Taylor Swift your way through. This is head and neck stuff. Athletes are literally KILLING themselves because of this. Remember Dave Duerson? Junior Seau? Both got severe depression from post-concussion syndrome. Both shot themselves in the CHEST. Not because it was less painful than the head - they wanted to preserve their brains for study of PCS.
3) Boston fans. Yes, I'll admit that "we" screwed the pooch on this one. I was there at the game, and I did think they were booing Toews. Maybe most were booing the penalty call - which was the right call, so that's lame too. And maybe I'm misconstruing it, but it did feel like it was a boo at Toews - especially since it started before the ref came to center ice. Perhaps they were booing out of frustration (2 points in 10 does that to you), but that's no excuse. And no, I didn't boo. (At least, not that time.)
Anytime someone's hurt on the ice like that, DON'T BOO. It sucks. There's nothing wrong with taking a half second to say to yourself, "How do I think other reasonable people are going to interpret my reaction?" I don't care if it's Matt Cooke. DON'T BOO. That's not what a hockey fan should be. Even players give stick taps to opponents who are carted off the ice after a big hit. Yes, Toews didn't need to be carted off the ice, but cheering for injuries is horrid.