I'm going to take a jump forward and actually look at what he's saying: 1) If you cover the purge valve when passing a regulator to another diver in need, you make it difficult for them to purge the reg when they get it. I think that's rather self-evident.
2) In order to avoid doing that, you have to school yourself not to cover the purge valve ANY time you are handling your second stage. This one I disagree with. When I put my own reg in my mouth, I have my palm over the purge valve in the rather natural motion I think most people adopt. HOWEVER -- When donating, I have hold of the hose next to the second stage. I've schooled that motion until it is instinctive. Even if I'm handing off my regulator to someone else in a totally non-emergent situation (eg. we've decided to share air for a while to equalize supplies) I hand it off the exact same way.
The two motions (putting a regulator INTO my mouth, and handing off a regulator to someone else) are very different, and I don't think there's any problem with learning different techniques to do the two things.
As anybody who knows me knows, I'm in favor of standardized procedures and protocols. But I also think you have to be careful not to overdo the process, and make people spend time training procedures that don't make any significant difference.