Yes, I’m afraid that you are still misunderstanding the research. Your linked article speaks about gene flow associated with the movement of pre-Proto-Germanic speakers to Scandinavia, but later Proto-Germanic formed in southern Scandinavia according to the longstanding consensus. This is clearly spelled out in the abstract: “Following the disintegration of Proto-Germanic, we find by 1650 BP a southward push from Southern Scandinavia.”

There’s no new theory here at all, just some nice archaeogenetic evidence to support a quite traditional view. FWIW, I work in a closely related field and am constantly reading Germanic–Finnic and Baltic–Finnic contact literature, and I can assure you this is old-hat stuff.