I believe Microsoft is well aware of this issue. I don't know what the
plans are, and I doubt that they will be publicly announced, or the
protection methods described--but I'm sure steps are being taken to harden
the app.
In the last analysis, if an administrator on the machine chooses to run a
trojan, the trojan can do anything the administrator can do. The two
viruses that disable Microsoft Antispyware so far fit this model. Similar
issues have beset major antivirus vendors for years now and haven't resulted
in major outcry about the reliability of the antivirus products.
Keep an eye on those system tray/notification area icons, and check out
their absence carefully!
