Well, I tried running it through virustotal.com for a second (multi) opinion.  That site picked it up as well, though again through Microsoft.  It's hard to say one way or another if it's a false positive.  Unfortunately, any sort of positive is enough of a deterrent in demo software. I definitely won' t be giving it a try until it's resolved, sadly.

I ve had the malware warning with the demo as well and not with the alpha neither. However, today the windows defender just deleted the soulash.exe by its own (I didnt even know that win 10 does that). It took me a while to figure out what the problem was. I "fixed" this by adding soulash.exe to the exclusions in the windows defender security center. Another thing to mention about this is that I usually keep my computer running for extended periods of time only going to sleep mode every once in a while. The sudden removal of the exe happened after a proper restart and while I was actually playing the game. It just kicked me out and the exe was nowhere to be found.

I hope that was helpful xD

I'm not sure if this will be of any help/relation at all or send you down deeper rabbit holes, but I'm on Windows 8.1 and the first time I run a new version of Soulash's .exe, Windows defender stops the program from running and pops up a warning that it is from an unknown publisher, from which I can resume operation normally. All this is honestly kinda standard on this windows version for me with any smaller early access titles, betas etc. Haven't gotten any of the weirdness that has been posted up above.