Furnace shutoff switch outlet only hot when furnace is running
Right after I asked this question I realized the blower needed to be running for EAC to have power.

:facepalm:

I moved HOT HUM to HOT EAC and now the humidistat will start the blower, which will power on the outlet that powers the humidifier's fan unit.  I also unplugged NEUTRAL EAC since I'm no longer using it.  Let me know if I did anything stupid here.