I'm not even sure Labardo actually makes contact with Grubauer's head, it desperately needs another angle or at least a better quality feed. It looks like his head doesn't even move until well after Labardo has already passed by him. The video provided shows Labardo turning to miss Grubauer and being tripped by him sticking out his left leg just as much as it shows Labardo viciously elbowing Grubauer. It's a pretty bad video to try to make the call on.
As far as Gudbranson being suspended for longer, it's completely understandable. It's an elbow, it's a charge, it's a head shot and it's after the whistle had gone. Let's not forget that he got a 5 game suspension in December for a hit to the head of Fontana (during a game where his team was losing 6-0) and was involved in an incident involving Garret Ross and Nathan Moon the night following this Labardo incident in which he jumped in as a third man and received a ten minute misconduct. The fact that he's a repeat offender and has a couple of incidents in the same weekend obviously has to be taken into account when handling something like this. Gudbranson brings a mean-streak and has straddled the line for pretty much this entire season, but you can't deny that he has crossed that line a couple of times this season. There are factors more than just the Labardo situations that came into play when determining his suspension.
As far as Grubauer, he's got a reputation as a diver and whiner in the OHL. He also never stops chirping on the ice, partially because he knows that guys can't actually touch him. That's what I gathered from what Archibald and a couple others have said about him, at least.