Just to clarify things... randori as practiced by us Shodokan folks is to help us learn Aikido against a strong and vigorous Resistance. It has nothing to do with sport. Because we don't want people to break bones or die (both happened) we have some rules more to do with safety than anything else. Still, it's hard word and shows you where your Aikido is lacking.
Shiai is randori used within a sport context with points, referees and a plastic cup at the end. It it not something that is taught in Shodokan dojo, you have to go out and do it yourself. Only way to learn.
Would any of this have helped whoever got stabbed in Michael Neal's story?... I have no idea. Would a stab proof vest have helped? I bet! http://www.stabproofvest.co.uk/sitemap/
in case you wanted to get one...