It is listed under actions, I do not argue that it is not mentioned there. I am saying it is so different from the others that I cannot see it as one of them, but only as a summary for how to delay any of the other actions and not as an action in itself.
Call it a should if you want to, I consider it so clearly not an action that even WotC listing it next to the actions does not make it one and was only done for textual proximity.
If WotC were infallible and always weighed things to the n-th degree, we would not have 100+ page discussions about how Hiding works and what Invisible means....