I'm assuming that, since instituted as a RUN (as opposed to a RUN ONCE), this is what avast intended --- for whatever reasons yet unbeknownst to us. As such, I have kept the startup entry intact. I have rebooted two or three times since, with no obvious/overt problems, so it seems repeatedly running this process is not causing me any harm.
Hopefully, someone high "in-the-know" will eventually reply, telling us WHAT this update is doing, and whether its continual running on each reboot is required or not. Ideally, avast can issue another RUN-ONCE update to remove this, if that's deemed the appropriate course of action.