MacOS – Why is the MacBook visibile on Bluetooth after Yosemite install

There is no more com.apple.mDNSResponder.plist in OS X 10.10. The service that controls mDNSResponder is now discoverd. The plist file you are looking for is actually:

/System/Library/LaunchDaemons/com.apple.discoveryd.plist

You want to add --no-multicast to the ProgramArguments in that file.

    <key>ProgramArguments</key>
    <array>
            <string>/usr/libexec/discoveryd</string>
            <string>--udsocket</string>
            <string>standard</string>
            <string>--loglevel</string>
            <string>Basic</string>
            <string>--logclass</string>
            <string>Everything</string>
            <string>--logto</string>
            <string>asl</string>
    </array>

Becomes

    <key>ProgramArguments</key>
    <array>
            <string>/usr/libexec/discoveryd</string>
            <string>--udsocket</string>
            <string>standard</string>
            <string>--loglevel</string>
            <string>Basic</string>
            <string>--logclass</string>
            <string>Everything</string>
            <string>--logto</string>
            <string>asl</string>
            <string>--no-multicast</string>
    </array>

You'll want to be very careful when editing that file. You can also use this script to do it for you - https://raw.githubusercontent.com/MacMiniVault/Mac-Scripts/master/disablebonjour/disablebonjour.sh

Updated/Better Answer:

1) This new script doesn't flash.

2) For reasons unbeknownst to man and logic (or just me), applescript sometimes/almost-always fails to Turn Bluetooth Off, if the System Preference window is in the background. Instead of turning off, what actually occurs is that Bluetooth immediately re-enable itself, so the pane is in a fresh state: it's ON, but no connections.

To overcome that, one way to to bring SysPref to the front, as in the original answer. Or, run a loop that click the button again (or for a 3rd time) until Bluetooth is really off. That's why there are two variables and a loop in the script. This should make the script more reliable. statName variable records the original status. Loop will continue clicking the button until status has changes. failSafe makes sure the script will not run forever in case of error. All at the cost of aesthetics of the code.

tell application "System Events"

    tell process "System Preferences"
        activate
    end tell

    tell application "System Preferences"
        set current pane to pane "com.apple.preferences.Bluetooth"
    end tell

    tell process "System Preferences"

        set statName to name of button 3 of window 1 as string
        set failSafe to 0

        repeat until statName is not name of button 3 of window 1 as string ¬
            or failSafe is 10
            click button 3 of window 1
            set failSafe to failSafe + 1
            delay 0.1
        end repeat

    end tell

    tell application "System Preferences"
        quit
    end tell

end tell

Original Answer:

tell application "System Preferences"
    activate --Change 1/2
    reveal pane "com.apple.preferences.Bluetooth"
end tell
tell application "System Events" to tell process "System Preferences"
    click button 3 of window 1 --Change 2/2
end tell
quit application "System Preferences"

From Accessibility Inspector:

button 3 in the the no.6 item on the list. The 6th button is no.11 in the list. When you call button 6 Preference Window goes Genie. I guess Mavericks had all the buttons bunched up at the front.