I doubt many airports that Ryanair fly to have the equipment for automated landings, but I do accept that one pilot is probably fine for most situations. However, I doubt passengers will accept it and many would be too scared - even if they're totally in the wrong. I doubt most people are scared to drive, even if statistically they're at much greater risk, but they do get rather frightened when flying because of the feeling that anything will mean death. In a car, you might just be able to do something yourself.
The fact is, in an emergency, two pilots are essential and you may not get a member of cabin crew into the cabin quick enough. Not only that, but they'll only be given the most basic of training anyway - they simply couldn't have the flight time and experience to do anything major.
And, not all serious incidents result in losing the plane completely and everyone dying on board, so I think it's fair to say that you want to at least give the 200-300 passengers flying a fighting chance. Could a single pilot do all the procedures to deal with an emergency?
I am not sure this idea was actually serious, although with Ryanair it's quite likely it was, but Ryanair has a good knack of announcing silly things like this to keep the press from noticing other changes. Create a load of controversy over this, while slipping out the announcement that all passengers are now going to be charged £5 to walk up the steps to board or something.