Sorry but no. Wii features parent control options. AT LEAST have an option to turn it on or off that you can add friends and stuff.
Again, not an excuse. If someone adds me and I think 'who the hells this?', a simple delete and we're back to not having them in the list.
I'd even say, and this would annoy me but would be forgivable, have the invite with a warning message that says something along the lines of 'there are paedos knocking about, be careful'. Obviously not that, but you get the picture.
Seriously, a simple 'turn friend invites on' in the parent controls would solve this simple problem. I can't believe you can defend this.