I think the author makes a strong point insofar as completely detaching ourselves from outcomes out of our control can't be done without lessening in some way our humanity. But the common human propensity is to be over-invested in external things that we can't control and that will not give us ultimate satisfaction, which is why Stoicism and other wisdom philosophies can be so appealing.

The question I would have for the author is, with what framework do you determine what is worth attaching to, worth grieving over?