FWIW, a lot of people talk about the 'predictable failure' of steel - that it does not snap or shatter all at once.

Well, bending is the first step in predictable failure - since it is bent it has failed... If this had been a failure of an aluminum or carbon steerer it may have been catastrophic. The advantage of steel is not that you can (or should) fix all damage, but that after a crash or impact the bike can still be ridden for a short while to get you home... after you get home, though, replace your fork.