Thanks for the great resource. And it clarifies how the quick boot works internally. It just a bypass to the hardware boot and it seems to reboot only the kernel and its modules.
Apart from patching, I had to change a setting of a driver module on a longer list of hosts, which required a reboot.
Anyway, I was only interested if there is a way to initiate it out of band and it seems it is more a preparation rather than an initiating the quick boot by using following cheating (taken from the provided document)
# Check the quick boot support
/usr/lib/vmware/loadesx/bin/loadESXCheckCompat.py
# Enable the quick boot
/bin/loadESXEnable -e
# Prepare the quick boot
/usr/lib/vmware/loadesx/bin/loadESX.py
# Reboot with standard tools like DCUI, ESXi shell, vSphere...
...
# Verify the result of the quick boot
cat /scratch/vmware/loadESX/loadESX.stats
PS: Is there an attribute to show at least the Quick Support of certain hosts?