Earlier quoted context omitted.
Why do you think he's using the term incorrectly? He just means that, with git, the order in which you apply patches matters. In a scenario where people are distributing patches and applying them as they receive them, this implies a lack of eventual consistency.
That's the lack of the associative property. Eventual consistency means that updates will eventually be propagated to all replicas in a distributed system and that all replicas will be consistent. Not the same thing, at all.
Commutative, not associative. And the commutative property is exactly what's required to guarantee eventual consistency when patches are being applied in the order they are received since it ensures that order of application doesn't matter. Of course, if you have all of the updates, you can achieve eventual consistency without commutativity by periodically reapplying all of the patches from scratch in a deterministic order. But IMO his intended meaning was both clear and correct.