Under these conditions, the rifle will not fire.

Regardless of what the liability lawyers wrote into the owners manual, the Browning/Winchester mechanism will not fire no matter how you manipulate the hammer with your thumb. Try it yourself. Hold the hammer fully back, hold the trigger fully back, release the hammer as quickly as possible. The hammer will not contact the firing pin. The mechanism cannot be made to fire unless you release the hammer by pulling the trigger.

If you attempt to lower the hammer, and pull the trigger before you have the hammer under control, then the rifle will indeed fire. But, this is a case of the mechanism doing what it was designed to do, fire when the trigger is pulled. I do not consider this to be an exception. The malfunction is of the nut behind the buttplate.

Furthermore, when carrying the gun loaded, the hammer is down and has insufficient stored energy to fire a cartridge even if by some unimaginable event, the notch broke and released the hammer from the half-cock position. If the Ruger #1 is carried with a loaded chamber, the hammer is at full cock. If by some other unimaginable event the safety malfunctioned and the trigger was pulled, the hammer would fall with full force.

As a fan of both designs (I own many of each) I really see this as a non issue. But I insist that there is no safety disadvantage to the Browning/Winchester design. If you wish to believe the liability lawyers, that's your concern.