The observation that there is a (very) strong statistical correlation between cranium and social size is an interesting and correct observation.

That much is true and uncontroversial.

What the article takes issue with is the exact number of 150, which can vary from person to person. But really, the criticism entirely misses the point. The number is just a rule of thumb derived from extrapolation. It's not a hard and fast rule like "You can only have 150 friends". Obviously.

Perhaps it should be something like cranial volume / body volume, or else we'd expect whales and dolphins to have massive tribe sizes, yet they typically hang with something like 20 peers.