I think this might be to do with the depth of resource, from...

I think this might be to do with the depth of resource, from historical looks like it's around .5m to 1.5m at around 5g/t. I was originally of the opinion that "why don't white metal resources just carry on with the resource", however going through the agreement they still hold some decent royalties on NSR and have a have a small allotment of shares in adv included.
It might be a case of chasing the best opportunity to turn a quick profit very easily. As for white metal minerals, they don't really need to do anything, no chasing investment, no planning, no producing, if it is a go ahead they will do well out of this arrangement buying only 1% of their NSR will cost 1 mill CAD.