The BGA were (are?) looking for a solution to the issue of a secure online source for children to play Go.
The main issue (having not read all the previous posts, sorry) is that of safeguarding rather than playing strength. As a parent I am nervous of sites which encourage chat and have the facility to send private messages.
I realise that a Go server is maybe a less likely part of the web for ne’er-do-wells to hang out and much of the concern might be unfounded but we (parents) are constantly urged to be super cautious with online activities.
I feel a separate class of account would be better - one which cannot join chat, receive private messages and such but can still play in the general pool. Ideally with a range of options like being able to chat in games or chat allowed and record available to parents and things like that.
My point is none of that is about the actual playing of Go or the rating system etc. There might or might not be other issues there but they are not specific to children.