I think the results are fairly clear because of what the file does, it could be used for good or evil (shutdown), so I would say avast could probably consider renaming this to something more appropriate. This one seems to be being caught by a generic signature (the -gen bit of the name), which I think is wrong, not that it shouldn't be detected but it should be detected in its own right as a riskware tool.
With tools (riskware) avast has a [Tool] suffix that it normally adds to the end of the malware name, which would seem more appropriate for this detection.
So you should send a sample to avast for analysis as outlined in the link that I gave about reporting possible false positives, though this one is a tool and should be reported as such.
If you installed this and are aware of it and accept the risk as such, then you could exclude it from scans.