um... by your logic an open source server (like, say linux) would be inherently less secure than a closed source server (like say windows iis).

open source projects have an unlimited number of people reviewing (and testing) the code, thus it's near impossible for mal-intents to hide backdoors. not to mention serious threats can be addressed quicker (because the contributors are also the clients).

closed source av projects have every interest in spreading fud, and no vested interest in addressing threats before they reach critical status.