I think it depends on how you tell TBH.
Something along the lines of "you will NEVER guess what your silly sharer did!" is both interfering and mean, however a chat that lets the owners know their sharer is struggling in some aspects and could use a kindly helping hand for a bit is going to do...
Perhaps, but mostly I think we need to agree on what constitutes what level although I feel the BHS has done the hard work of that for us.
The stage 1 exam is exactly what a novice should be aiming for- all the basics in place ready to move on.
Not the most elegant looking rider but safe and...