DFC seems to be trying to make a point about NPPL holders and adding an SEP with a CRI training - which of course you can't do, it would be an SSEA. All of which is a total red herring to the original question as nobody is trying to add an SEP to a NPPL from what I read of the debate.
The main thing a CRI can't do is if the student involved wanted a JAR-PPL from an NPPL he/she would have to engage the services of an FI, don't think anyone is disputing that.
Before I became an FI, I was a CRI and successfully trained numerous NPPL microlighters for their SSEA ratings and also a lot of people renewing SEP ratings on lifetime PPLs - all worked out fine.
I think the CRI is a great rating as long as people holding it and training with it know their limitations (it is only gained with minimum training) and are working in a supportive environment. I work with other CRIs now, and for example I know if they get a student for a rating that really needs a lot of work on core flying skills (landings for example), they might pass him/her over to an FI for a couple of hours brush up then continue on. All quite sensible and pragmatic.