To be fair, lots of people doing it is no indication of anything.We've had thousands of users download the mod with no issues. I can assure you that it is safe.
But the suspicions of the scanning website are about methods used by the launcher that can be used in certain patterns of malware, and can be explained to be legitimately used by the launcher.
For example it can be alarming if a program immediately connects to the internet when launched, but with this program it is obviously necessary.
Not saying the launcher is safe. It just absolutely most likely is.