I’m not sure in that case if it’s Quicksilver that needs access, or the script. I use QS to access a network folder directly all the time and I don’t remember it asking, so that’s probably covered by giving QS Full Disk Access.
Can you add the script to different categories in the Security & Privacy prefs? If not, maybe if you save the script as an application, it will let you?
You could also try resetting all the prompts with
tccutil reset AppleEvents in Terminal, but that will require you to re-approve a bunch of activity.