The rules don't seem to be clear on this and some clarification is needed. I'm thinking that Sir Neil is a qualified referee so his opinion has some credibility and he thinks it's okay.
If we can get away with it we should do it more, and if we do it'll catch on. Reminds me of when Gareth Edwards hid the ball under his jersey out of a scrum and ran through with it, and at that time there was no rule to prevent it so it stood.