That's fanon. Yeah, I sort of like the idea too, and yeah, Goldsmith to some extent may have styled the First Contact Borg leitmotif after V'ger's from TMP, and yeah, maybe he did that deliberately, and yeah, somebody's friend of a friend said that Gene Roddenberry once coughed in a way that could be interpreted as suggesting he'd had in mind the Borg creating V'ger all along - but it's fanon all the same.

(Me, I like Ron Jones's theme from The Best of Both Worlds a lot better, anyway...)