This is really a huge deal!! I can confirm this:
bcdedit /set {bootmgr} bootshutdowndisabled 1
working on the following system:
Intel Xeon E3 1231 v3
Asus H97-Pro (UEFI 2705)
4x 4096MB Kingston KVR1333D3N9/4G
Samsung SSD 840 EVO (Firmware EXT0CB6Q) (Hardware Accelerated Encryption)
ASUS Strix NVIDIA GeForce GTX 970
Enermax MODU87+ 600W
Windows 8.1 Pro 64bit
There is a MSDN page that documents the setting (https://msdn.microsoft.com/en-us/library/windows/desktop/aa362652%28v=vs.85%29.aspx):
"BcdLibraryBoolean_BootShutdownDisabled: Disables the 1-minute timer that triggers shutdown on boot error screens, and the F8 menu, on UEFI systems."