You could have kept this with your other topic as it is basically the same.
As I said there:
Clearly not a false positive as it can a) restart your system and b) it is flagged as a PUP Potentially Unwanted Program. The restart function in the hands of a malicious attack would be one use of the tool, but in the case of SDfix would be if it is required to restart the system to remove in use malware, etc.
So you could chose not to do anything (block) since you downloaded it. It would of course be detected next time round, so you would have to exclude it from scan if you wish to keep it.
However, there is little benefit in keeping this tool lying around if you have used it, these types of tools should be downloaded before they are used (that way you have the latest version) if you suspect you have the infection it deals with.
Another point you are doing a custom scan as PUPs aren't scanned for by default.
