Yes that is the line that tells OCLP to emulate a Virtual Machine, which is the mechanism for enabling updates OTA. Yes, each time you Build and Install Open Core it replaces the revpatch line so get everything the way you want it first, then edit out the line. When you are ready to install updates, just Build and Install, reboot and its back.Do you mean delete revpatch=sbvmm (NVRAM > 4D1FDA02-38C7-4A6A-9CC6-4BCCA8B30102)? Clever.
Would this need to be manually edited after each OCLP > "Build and Install Open Core"?
Also, I see lots of talk of keeping an old MacOS version on an external drive so you can install Firmware Updates, but I have done hundreds of Macs in the last few years and you can easily update the firmware from within an OCLP booted non-supported MacOS version as long as you extract the .scap files from the newest MacOS installer. Takes just a few minutes and no need for a backup OS or external drive to apply updates to.