MacOS – Can’t quit app launched through launchd

As it says in the title, "Can't quit app launched through launchd"—or more precisely, I can quit it, but it then automatically restarts again.

Background: I prefer to use BusyCal, not iCal, but there are some calendar-ish things that have to be done by iCal before BusyCal can get the results. I figured I'd create two launchd scripts: one to launch iCal every day at 5 am, and another to quit it a few minutes later.

Here's the plist to launch (in ~/Library/LaunchAgents/com.dori.iCalLaunch.plist):

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
 "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>KeepAlive</key>
    <false/>
    <key>Label</key>
    <string>com.dori.iCalLaunch</string>
    <key>OnDemand</key>
    <true/>
    <key>ProgramArguments</key>
    <array>
        <string>/Applications/iCal.app/Contents/MacOS/iCal</string>
    </array>
    <key>ServiceDescription</key>
    <string>iCal Launcher</string>
    <key>StartCalendarInterval</key>
    <dict>
        <key>Hour</key>
        <integer>5</integer>
    </dict>
</dict>
</plist>

My understanding was that I didn't need the KeepAlive and OnDemand keys, but I put them in anyway to try to stop the relaunching.

Here's the plist to quit (in ~/Library/LaunchAgents/com.dori.iCalQuit.plist):

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
 "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.dori.iCalQuit</string>
    <key>Program</key>
    <string>/usr/bin/osascript</string>
    <key>ProgramArguments</key>
    <array>
        <string>osascript</string>
        <string>-e</string>
        <string>tell application "iCal" to quit</string>
    </array>
    <key>ServiceDescription</key>
    <string>iCal Quitter</string>
    <key>StartCalendarInterval</key>
    <dict>
        <key>Hour</key>
        <integer>5</integer>
        <key>Minute</key>
        <integer>10</integer>
    </dict>
</dict>
</plist>

Based on my log files, they both run just fine—but after the Quit runs, iCal relaunches.

Any ideas for things to try, or things that might be causing this?