That's not how it works. AV software searches files for signatures of known malware and possibly for indications of suspicious content in files. There is no database of "safe" files. A database containing just some kind of hash of all current and past versions of the many thousands of windows system files alone would be enormous, not to mention all the other software (like MG casinos and their frequent upgrades).
There are lists of known malware files, and it seems that for some reason the casino installers keep looking like malware.
Perhaps the problem is with the casinos being "too clever" with their installers, and this is confusing security programs.
Players used to be able to download a casino to the desktop, scan it, and then execute the install directly from the desktop, What players NOW download is NOT the installer itself, but a "manager", a tiny utility that THEN proceeds to download FURTHER files that make up the casino installer itself. It seems THIS is what gets picked up by security software, since this is EXACTLY how a TROJAN operates, and it is hard to tell the difference.
Rather than trust their security software, players have to trust the casino when they say their installer is just that, and not a piece of malware.
Casinos could solve this by going back to using simple install files, which the user can download completely, and then execute FULLY behind their firewall and security protection, and with NO internal connection requests being necessary from the installer.
The difference here is that the USER downloads the full "exe" using the browser, and since such a download is permission controlled, it does NOT trigger the security software at this stage. When executed from the desktop, a complete installer ALSO does not normally trigger the security software because it does not BEHAVE like a trojan by trying to "call home" during it's execution.
This does not happen when a casino is installed from a CD, yet install the SAME casino from the internet, and it WILL trigger the security software, even though what is being installed is the SAME in both cases.
Poor design is creating unnecessary worry from players, but is also losing casinos potential customers, those who do not feel they "know enough" to make that judgement call to disregard the warning as a "false positive", and so delete the file rather than trying out the casino. This also means they are unlikely to install the casino at a future date.
Quite a few users don't even know HOW to override their security software, even if they wanted to. In a work environment, they would not even be ALLOWED to, and it does seem that casinos promote "playing at work" to their players by suggesting how it can be achieved. Lately, this has been through the development of the "mobile casino" rather than getting players to install the software on work machines. Although this does not compromise the workplace machines, it STILL encourages employees to misuse the working day.