Don’t worry about raising this, it is highly relevant, and in fact included on our list of media “gotchas” - people love a good debate (or argument).
Unclear whether this person had a high degree of technical knowledge but didn’t get specific with you, or whether they were simply naysaying with little grounds to do so.
If they were referring to repair documentation, we simply do not have access to it because manufacturers go to great lengths to restrict access, and we use mostly what we can get from other fixers on the internet.
If they were referring to physical materials, we would never advise anybody to use components or materials that are not safe. In fact, often times we help people understand they have been using the wrong power supply, or they have used the wrong fuse. So in fact we end up righting a wrong.
In terms of spare parts, this is a highly complex area. To simplify, we generally advise people on their options, and warn against anything that appears to be too cheap or “too good to be true”. In fact we usually err on the side of conservatism.
As for “competence” and the law, there is nothing in UK law that prevents talented amateurs and DIYers from helping others fix their electronics and appliances for free. That said, we are actively creating and maintaining our own norms for addressing risk and safety in community repair, as we implement our own safety procedures and reinforce an atmosphere of vigilance around safety issues.
Hope this helps? Thanks for raising this, I’m sure you are not alone in this!