Rhinelanders only come in tricolor
" American Rabbit Breeders Association - white with black and orange markings and white with blue and fawn markings. " Rhinelanders never come in wild type agouti.
Also, rex is a recessive gene, so if you breed a rex to a non rex rabbit the fur comes out normal texture. I have a whole litter of rexXnz right now in my bunny barn and they're all normal fur. It's a really easy gene to work with. I think he's probably just charlie colored rather than a rhinelander - which is he has two copies of the broken gene resulting in minimal coloration. Though he could be a normal broken with a LOT of white. It's hard to say.