Standing submissions are low percentage and highly poor choice of solution for a self-defense situation. I think keeping the fight standing when he outnumbered and out-weaponed his opponent was a mistake. Attempting a RNC while hanging from the back of his larger opponent was a bad decision. Attempting a RNC in a possible weapon situtation, standing or on the ground is a bad idea.
No one on this thread has claimed a solution that would be knife proof or magical. No one claimed a new type of takedown that would prevent someone in all scenarios from deploying their weapon. There are lots of things that can and should be done in these types of scenarios to minimize the ability and opporatunity for the opponent to deploy a weapon and/or use it.
You went for a choke on the street from someone’s back without taking them down or hitting them, without any semblance of control.
These words were exactly what I meant when I typed them. DO not go for submissions without first taking them down or hitting them. Control and dominant position are two vital element when attempting a submission. Many holds work standing up, but you must still have dominant position and control over your opponent. In both UFC's you posted, neither man was able to improve his posture or otherwise conter the standing/hanging RNC because the other man had complete control. Neither of those men had any sort of weight advantage.
Hopefully I have cleared any confusion I caused by not taking any deep breaths.
I was not trying to say that a takedown is the answer to a knife weilding opponent. My point was that any opponent, knife or not, is easier to control on the ground, and that it would have better for him to have ground his opponent being that him and his boss outnumbered him. The more options you can take away from the bad guys the better. Hanging out of some big guys back trying to choke him is a bad way to deal with a real self-defense situation. I believe that in any encounter you should always be working for better position and control, long before you attempt any sort of submission. I also think you should be constantly pounding away at your opponent, and using any weapons of your own.