Windows Defender is wrong, of course. Antivirus software makes guesses, since virus authors are constantly making variations. You can upload the installer file to http://virustotal.com and see scan results for 65 different antivirus programs, though you may need to disable Windows Defender to be able to download the file at all. For example:
https://www.virustotal.com/#/file/e8256ffa1d7e2155cb1dedf7972890e45f7894eb091c7d34c5d816ff658e8c9a/detection
We have tried to submit the incorrectly classified files to Microsoft using the official method, however at the last step Microsoft's website is broken (gives a "500 internal error"). Pretty amazing for a 110 billion dollar company. It also goes to show how much they don't care about the accuracy of Windows Defender.
We are working on getting Spine digitally signed which will cause Windows Defender to treat us more favorably, but there's a bunch of hoops that have to be jumped through. We are currently waiting for other companies to do their job, until then the process can't move forward.
