Andrew your response directly conflicts with a response from Symantec employee EMercado on 10 Dec for the similar question:
Does Symantec Patch Management require the wuauserv service to be running?
Created: 10 Dec 2012 | 1 comment
His response was:
Yes, the Windows Update Agent is necessary because Patch Management runs the actual patch binaries from Microsoft, and those require Windows Update Agent. Altiris is not recreating the binaries themselves, just packaging the command line runs.
Which is the correct answer?