Sorry David. My friends on the Outpost forum agree that there is no way to block an executable the name of which is unknown until it rattles Outpost's cage. Also there is no way by which the contents of folders can be excluded from action by Outpost. I am requesting that Agnitum considers this issue.
Outpost appears to be programmed to take an extremely conservative view, i.e. not implicitly trusting digital signatures of executables, however worthy their provenance. The net result is Outpost crying 'Wolf!'
I appreciate that Outpost user woes are not the concern of Avast. However, the problem of the emergency executables could have been anticipated and is disruptive for those who are not using Avast firewall which presumably is programmed with consideration of the emergency executables.