It's not a terrible argument. To put it differently, the value to the end user is not a direct function of the degree of openness, but the utility of the degree of openness.
The narrative of Sophie measures this utility.
The narrative of Sophie measures this utility.
The part in the title about "The iPad is 99% more open" is 100% semantic bullshit (which happens to be a pet peeve of mine, obviously). Additionally, "None of this crap about it being closed is accurate." is wrong because he's talking about open (as in accesible) while the people he's saying are wrong talking about it being closed (as in freedom). No one was making the argument that it's not accessible to users, so it's a strawman. I don't think it was intentional though, just a failure to think about the fact that he's using a completely different definition than the people he's arguing against.
He does have a point, but it's also stuck in the middle of this confusion over terms. His argument that "None of this crap about it being closed is accurate." is indeed completely wrong, because that claim was never made. The point about the perceived complexity is correct, but again I don't think that has to do with the inability to install from other sources.