I think what's meant is that the event stream can be reordered and give the same result.
This isn't necessarily an abuse of terminology - I believe if we look at an operator that takes sequences of events and appends them, what we're talking about is in fact commutativity of that operator (in terms of the impact on the system).
You're right, you can line the two concepts up to some extent. (I mentioned CRDTs because they're one way to do that in a particularly nice way.) But given the context of the question, it seemed like teasing out the difference would be helpful.
This isn't necessarily an abuse of terminology - I believe if we look at an operator that takes sequences of events and appends them, what we're talking about is in fact commutativity of that operator (in terms of the impact on the system).