Well, technically speaking, above all else it would have been not just good etiquette but the bare minimum for this chap to come over and see that you are all ok. Of course he didn't hit it into the trees on purpose but "sorry" is the least he should offer.
You didn't say whether this chap was playing the same hole as you and if so did you waive him through? This brings up a whole new set of questions.
Getting back to your question...
I can safely say that should anyone be unfortunate enough to be knocked out on a golf course it would stop play particularly for them. For the rest of the group play could continue although during winter months care should be taken not to leave unconscious bodies in snow for too long as frostbite may affect that players ability to dial for assistance when they come round.
Almost all groups on a modern golf course will have at least one person with a mobile phone and the clubs phone number is usually on the scorecard. There will usually be a first aider on site and an ambulance should be called if there is any doubt.
Insurance for golf injuries is available privately and many golf clubs these days include it in a green fee. It is however a risk you are accepting when you walk onto a golf course that accidents happen. Good manners and common sense are the main tools golfers should use in these situations.