I am afraid you are right about this article just further muddying the waters regarding "early blue beads" since this variety also continued well into the 18th C. But the main point here is blindly accepting 14C dating over well-established dating of the early blues considering how inaccurate some 14C dates are for recent (post medieval) materials.

One also has to carefully look at how the beads might have arrived in Alaska prior to 1500. They didn't just drop from the sky. I looked carefully at the history of European (and Eastern Asian) incursion into the region and no one is mentioned until considerably later. It is, of course, possible that a handful of beads was carried by numerous consecutive individuals from Western Europe to northwestern Alaska prior to 1550, but considering the huge distance, not very likely.