Im in Texas so right now I can’t safely power up the computer because the power here keeps turning off. Soon as the power is back in a reliable state I’ll do a scan on what came out of the install .exe and see if anything shows with that. For a virus scanner to reliably scan a compressed file it would first have to expand all the files then scan them one by one - I’m not familiar with any AV that does that. It’s quite plausible that the compressed .exe just happens to have a series of bytes that matches the signature of one of the eleventy two billion virus’s in the wild. That’s a common problem.
You might could try one of the beta versions before 8.0 that works with MSFS2020 and see if they scan ok - I ran with all of those with no Mobiflight issues.