Isn't it the team's productivity the manager's responsibility. And if one player is not playing the game so to speak (holding / blocking a flow of information for an hour even if it is non-urgent) then shouldnt they follow up? Maybe not after one time... But, it seems the right thing to do from the manager's perspective?
First, it's generally a management failure if there's routinely questions to be answered or information requested that needs to be answered within an hour. Whether that's a planning failure, or a documentation failure, or whatever it may be, that underlying problem should be addressed because...
Knowledge workers benefit greatly from being able to enter a state of deep concentration. When I'm interrupted while I'm working, it's going to take time for me to get back into the state of mind I was in before the interruption. Cal Newport (the author of the post) has written a lot about this with his "Deep Work" material. Yesterday, for example, I was interrupted 3 times while trying to watch a 15 minute video related to a problem I was trying to solve; how well do you think I absorbed that material compared to being able to learn it uninterrupted? When I'm debugging a tricky problem, it's very likely that I have a pile of conscious and subconscious thoughts going on in my head; if I have to switch and answer an email (or have my manager come and ask me a question), all of that context evaporates and I have to start over.
So, yes, from the manager's perspective it seems like a good choice, but it's very likely going to be highly disruptive to the person being asked.
Fog Creek is a nice case study. Everyone gets their own office with a door.