I think being platform agnostic can be harmful too, definitely having access to and actively using multiple platforms can give you great insight into what a given platform is doing right and wrong. I'd go out of my way to encourage that, because then we are adding value to different discussions across the board by having that unique perspective. I'd just hope that someone that's being an ambassador for WPCentral might have a WP device as their daily driver. Or at least have a vested interest in the platform and know enough about it's day to day news and information to be able to help out people here on the forums. Clearly that's what's happening with BergerKing etc, even though they don't use the platform they represent day to day.
This is where my concern is with LaRue, he's gone and said he doesn't particularly care about WP he just wants a good phone, which is fine but I'm not sure if that means he's likely to stick around if his next phone isn't on WP.