Yes, talk to your brother about it. Try to stay calm so that your anger doesn't show through. You're not angry at him; just concerned for your nephew.
It's super weird, BTW, that the US chapter of Boys Brigade has no website (or rather, it doesn't seem to load for me: http://www.bgbrigade.org/
), while chapters in other countries have perfectly functional websites: http://www.boys-brigade.org/national_links.php
So... trust your gut. See what's up.
edit: Oops, just realized you're in Australia. So my concern about the US website is totally useless. Sorry.