> Is it the call to menubar per se?

Yes.

> Is it the way the injection into menu works i.e. the code introduced in ba8f147 ?

There was no new code introduced there, it's a revert of the deletion of the entire plugin. If you're trying to point out something specific, that commit is not useful.

> Is it the wrapping of this action set in a semantically meaningful method name?

Yes.