I suspect Ruger will offer this free "upgrade" until the cows come in. In these days of class-action/get rich lawyers trolling for a victim wanting to sue a big company, those non-hammer block 3-screws are just a huge lawsuit just waiting to happen!
BTW, if your friend has his Ruger converted, Ruger will also return his original 3-screw's parts in case he wants to convert it back for sale to a collector. It is claimed that the upgrade does not harm the gun in any way.
I once hunted with a 3-screw Super Blackhawk in .44 Magnum. I can't tell you how many times I quietly cocked the hammer back, thinking a deer was approaching . . . only to have to lower the hammer quietly when the deer didn't materialize. This meant that many nights in the dark I couldn't remember how many rotations to turn the cylinder so the hammer would be over the empty chamber. I'd have to get out a flashlight to tell . . . and I hated to do that in the dark before descending from the deer stand.
Alas, I finally traded it off for a Model 29 S&W and never looked back!
The 3-screws are much loved guns though . . . as long as one is careful! Then again, so is the old Colt "Peacemaker" . . . another famous revolver without a device to block the hammer from being able to contact a live primer.
T.