this might be an obvious thing, but did you actually download the workflow and installed it?
even if you did the sudoer part wrong, it must still work and ask for your password. it worth nothing that your windows partition must be named as BOOTCAMP (where you see /Volumes/BOOTCAMP/ in script).
if all that failed, you can change the script to the one below:
tell application "Finder"
set iconPath to (get name of startup disk) & ":Applications:Utilities:Boot Camp Assistant.app:Contents:Resources:DA.icns" as alias
end tell
do shell script "bless -mount /Volumes/BOOTCAMP/ -legacy -setBoot -nextonly; shutdown -r now" password "YOURPASSOWRD" with administrator privileges
this one have your account password in it. Remember to change YOURPASSOWRD.