I'm no stranger to armchair critics, pilots do it all the time and usually the end result is good for the critics. It's not a bad thing to do, as it usually can result in people truly evaluating what they would do in that circumstance and how they would prevent it. There are some educational aspects of it, provided you keep it reasonable.
The educational lesson here is to be better equipped if you lose the rudder. I also think that the captain handled himself fairly well, in the situation anyway. He let someone know what was going on, where they were, and left his options open. He then disregarded his interest in the boat and accepted rescue when the alternative was far riskier and more strenuous to himself and the crew. He should have been more involved in the repairs from the start and he should have realized, especially after having problems several times, that there should be some alternative rudder in case it fails again.
That said, I find it ludicrous that most of you would turn down a rescue for the sake of a boat when there is a crew on board, no rudder, and rising seas. Especially after having been told your current location has very little commercial and pleasure traffic, so chances of another rescue would be slim. Would you really risk the circumstance and put yourself and the crew through that type of situation and with those risks? For what? Your boat? Your pride? It is the height of arrogance and selfishness to put the needs of the boat (and your interest in the boat) above that of your crew. The safe decision was to abandon ship and accept failure.
They likely could have survived and finished the journey, but they would have had a higher risk of bigger problems down the line. There are plenty of people who have had to do this and will probably be more in the future, but it doesn't mean that continuing on is always the right decision. I'd have done the same thing he did.
Also perhaps another argument for a devided rig. I've used my backwinded mizzen sail to turn the boat 180 deg before when our engine was disabled and there was no forward boat speed due to the true wind being only 0.5kt. I imagine a ketch or yawl would be much easier to try and sail without a rudder than a sloop.
I would imagine that the rudder acts as a lateral stabilizing force when in place, as part of the design of the boat. As a result, I don't think your ability to steer without a rudder (or keep a straight course!) would be as good. In other words, testing on a boat with the rudder in place may yield different results than one without the rudder.
That's just a theory, though.