I had to go back and listen to this pod cast.
As Brian Moore said at the end, I can see both POVs.
I have always thought that if you take another player to ground in a ruck but you do it way from the ball (so that the ruck could still be competed at by counter rucking for example) then play on. If you take someone to ground onto the ball then you must roll away.
The judo roll is coached so you roll a play away from the breakdown so I can see what NO is saying, however I think Ben Ryan was arguing a different point really. What he was tying to say is "should a judo roll be allowed because it is dangerous and severe joint injuries can occur"
I think BR is correct, you only have to look at Eng training camps when a number of high profile injuries have happened during judo sessions, I am very hypocritical though.
Having only just stopped playing at Level 6 as a #7 weighing only 13 stone there is sometime no other technique that effectively remove a player from the breakdown so I used to use it. I have been on the receiving end of it and have known my foot and knee were in a bad place, I have in the past felt the judo roll coming and have purposeful collapsed onto my knees and taken my hands off the ball, I have relinquished the turn over and the oppo have played the ball out of the ruck.
I think what Ben Ryan is getting at is that in his opinion, for safety, there should be a law directive to say "Judo Rolls are now illegal", rather than a change in law specifically just guidance that they should not be allowed.
