The magazine sticks out too far for styling reasons.
I don't see "style" in "short, light, and handy," though I will concede that to some the long magazine might detract from how "handy" they perceive it to be. But if that's the case, there are now the 5 round polymer magazines to address that, and even help a bit with the weight.
I concede, too, that tricked out with a scope and sling, and a five round polymer mag, the rifle is still likely (I have not done any scientific analysis) to be a bit above the upper end some times quoted for the weight of a "legitimate" scout rifle (7.7 lbs). But not by much. And if that is all that is left of criticizing it, then it comes close to the Cooper ideal.
Then the question becomes what Cooper might have thought about that. And no one knows. Not even you. The OP made a point about what he thought Cooper would think of the GSR. You disagreed. I cited a source to suggest that others think Cooper might have like the GSR. You still wonder about that. And that's all we can do, unless Cooper speaks to us somehow from beyond the grave.
Meanwhile, let's shift the focus of the debate a bit. It seems that the idea of a scout rifle, along the lines conceived by Cooper, has become, or is becoming, a popular notion among shooters. So the question I have is this: If the idea is popular, and Cooper's criteria are so determinative of what we think the scout rifle should be, then why aren't there more commercial rifles that satisfy the criteria? The benchmark is the Steyr, of course, but it is very expensive. Is that the problem, that Cooper's criteria are hard to satisfy in a mass produced rifle, without going to a lot of expense? Besides having some specific ideas about what a scout rifle should be, I think Cooper would have wanted it to be available to everyman as well, and not a rifle just for the elite. And maybe that is just not possible, without some compromises.
In the end, no one knows what Cooper would have thought about the GSR. Perhaps he would have approved, on the grounds that while not perfect, it was close, and at half (or one third) the price of a Steyr, made it more accessible to the common man. Who knows?
Moreover, while Cooper "owned" a particular definition of a "scout rifle," the idea antedated his formulation. So while the GSR might not meet Cooper's criteria precisely, as has already been noted, many do find it "short, light, and handy" and thus deserving of the descriptive term "scout rifle" on its own merits.
The term "scout rifle" has come to apply to a lot of variations that might not meet Cooper's criteria, strictly speaking. If beauty is in the eye of the beholder, perhaps "short, light, and handy" is also. I understand why you challenged the OP's remark. He cannot know what Cooper would have thought of the GSR, any more than you can. We can make some objective assessments, as you have done with weight, and point out where it falls short of Cooper's criteria. But that doesn't nullify calling the GSR a "scout rifle." If enough people think of it as a "scout rifle," that it what it is. I own three "scout" rifles, none of which would meet Cooper's criteria. Some would rather refer to these types of rifles as "Pseudo scouts." But that enshrines Cooper's definition as the only possible one. I do not buy that. Cooper deserves all the credit we can give him for popularizing the concept, and giving it concrete expression, but with language being what it is, no one can stop the term "scout rifle" from being used to refer to guns that do not meet his criteria perfectly. I'm not so sure that he would mind that, as long as he got the credit for the general idea. But again, who knows?