Can you disable a code signature check?
I got the patch to work after running sudo spctl --master-disable. I don't know if there is any way to use spctl to target only rcd though.

Replacing the code signature with an ad-hoc identity with sudo codesign -f -s - /System/Library/CoreServices/rcd.app/ didn't seem to work. Edit: but as mentioned by user48986, it works if you specify the path to the executable, like sudo codesign -f -s - /System/Library/CoreServices/rcd.app/Contents/MacOS/rcd.