Rudder Fell out underway.

I have a friend that owns a Nautique 226 that he recently purchased used. When he bought it, the boat appeared to be meticulously maintained from a person with more than enough means to do so and keep it that way.

Anyway, he was pulling his kids on a tube around the lake and immediately lost all rudder authority on the boat. I was not on the boat, but it appears the rudder suddenly just fell out. They got the boat stopped without issue and used a towel to Plug the hole as they were obviously taking on water fast. The boat was towed to a dock and put on the trailer without further incident. He did reflect that the boat seemed difficult to steer, but was under the impression that was the way it was.

With that said, does this sound like something that just happens? I am not an expert on his boat, or rudder connections in General. It seems to me this could have been cause by faulty Maintenance, Parts, or Sabotage.
The question I have is, how probable is it for the rudder to just fall out?


Thanks.