I'm sorry to tell you that but that's not true.
The switch FBW Disabled has been renamed FBW Gain mode for a reason. And that reason is, you can't bypass the FBW computer system.
The FBW gain mode switch give you more control over the control surfaces but is recommended for a specific flight envelope. Flying at supersonic speed with FBW Gain mode ON is quite a rodeo, just give it a try.
That doesn't answer your main question but it is important for you guys, Mirage pilots, to understand the FBW computer cannot be turned off or bypassed. As Azrayen says before, if FBW was really off (for any reason) your only option would be ejection.