But when yhou are saying this it means that Perez under no surcomstance could rightfully defend his position. If you watched the footage you clearly can see that Perez is braking in the right spot and is choosing a defensive line to the inside of the corner in a straight forward manor not weaving and changing lines. On the other hand Massa is following the track layout steering to the right into the car that is in his path. Is still do think Perez is not to blame and this case is comparable with Monaco for that manor. I think both are simular mistakes and not needed to be punished at all.
They are not that similar, as in Canada it was the guy behind who kept his "line" while in Monaco it was the guy ahead.
He could defend it, but he needs to make his intentions clear a bit earlier, and start to move before he start to brake, as soon as you have started to brake, any kind of moving from one line to another is a no-no in my book, and from my experience.
Again, I totally see what you mean, I just don't agree with you, and I think it's right that Perez got a penalty (if someone had to get a penalty for it. It would've been better to called it a race incident and move on).
Just to make my view totally clear here: I mean, from my experience, that Perez should've started to move a bit earlier, as he should change lines under braking (he stops turning when the track is turning, and is by that, changing line while braking). However, a slightly bigger margin from Massa wouldn't have hurt at all, Perez could've locked up slightly and drifted a bit out as well, and it would've happened anyway. Thing is, I don't think Massa did anything wrong according to the rules, while Perez, if he hadn't started to turn at all, or turned left (gradually going left, compared to the white lines all the time), would've been clear. But he didn't.