They were visual. There is a reason for that button.
Link to a Honeywell page about the terrain clearance floor:
here...
Inhibiting the EGPWS without specific instructions from manuals, NOTAMs, etc. is like turning off the TCAS if it shows an aircraft approaching. Especially at night with cloud cover, when it's hard to say you are truly visual with terrain, obstacles, etc.
Does RWY 18 at Birmingham has any official guidance in this respect? I only have performance data for 06/24...