Do you think I'm misunderstanding something other than that I'm not drawing the same distinction between proto-Germanic and "paleo-Germanic" that that paper appeals to?
You've quoted something that says after proto-Germanic had diversified, daughter lineages left southern Scandinavia to establish themselves elsewhere in the world.
But I pointed out a completely different idea in the paper, that before proto-Germanic diversified, about 2000 years before the time you mention, its speakers arrived in Scandinavia from "the northeast coast of the Baltic".
You've quoted something that says after proto-Germanic had diversified, daughter lineages left southern Scandinavia to establish themselves elsewhere in the world.
But I pointed out a completely different idea in the paper, that before proto-Germanic diversified, about 2000 years before the time you mention, its speakers arrived in Scandinavia from "the northeast coast of the Baltic".