It seems like the consensus over at another discussion on this topic
[1] is that we ought to go ahead and print the zeros [for machine
readable output formats], even though that creates some interesting
scenarios like the fact that disk sorts will print 0 for memory even
though that's not true.
The change has already been made and pushed for hash disk spilling, so
I think we ought to use Justin's patch here.
James
[1] https://www.postgresql.org/message-id/2276865.1593102811%40sss.pgh.pa.us