Windows defender is detecting the .exe as a trojan. Is this normal?
Unfortunately, yes.
Antiviruses may arbitrarily decide the exe is a virus using their euristic process. It literally means it tries and "guesses" that a given program is a virus because of some operation it does (EG: code obfuscation to prevent data reading from outside).
Fusion 2.5 games often are considered viruses even if they are not. If you search on any search engine you can see it happens far too often...