I just put this together quickly, but haven't tested it. should work... Might need a logout/login before the text is picked up by the screensaver.

#!/bin/sh         

#Todd Houle

#1Sept2016            

ssTEXT="Meat is Murder"



UUID=$(/usr/sbin/system_profiler SPHardwareDataType | awk '/UUID/ { print $3; }')

LocalHomes=$(/usr/bin/dscl . -list /Users NFSHomeDirectory | grep -v /var/ | grep -v /Library/ | awk '$2 ~ /^// {print $2;}')



## FEU                            

for OneHome in $LocalHomes; do

    defaults write $OneHome/Library/Preferences/ByHost/com.apple.ScreenSaver.Basic.$UUID.plist MESSAGE "$ssTEXT"

    owner=$(ls -l $OneHome/Library/Preferences |grep ByHost|awk '/ByHost/{print $3}')

    chown $owner $OneHome/Library/Preferences/ByHost/com.apple.ScreenSaver.Basic.$UUID.plist

done



##  FUT

defaults write /System/Library/User Template/English.lproj/Library/Preferences/ByHost/com.apple.ScreenSaver.Basic.$UUID.plist MESSAGE "$ssTEXT"



## Fix user template

/usr/sbin/chown root /System/Library/User Template/English.lproj/Library/Preferences/ByHost/com.apple.ScreenSaver.Basic.$UUID.plist

/bin/chmod 700 /System/Library/User Template/English.lproj/Library/Preferences/ByHost/com.apple.ScreenSaver.Basic.$UUID.plist

The scrip works great. Thank you. To change the settings immediately and not have to powercycle or logout/login, just add the following to the end:

killall cfprefsd

Works great for me.

@thoule is it working for Monterey?