I like the idea of V'ger being related to the Borg, but not necesssarily directly so. If the machine planet were a different offshoot of the same tech that the Borg came from, they'd be cousins, enough to explain Spock's situation in the Shatnerverse without making either one causative of the other.
Even better than saying it is or isn't is making fans wonder...
Sounds like the "Small Universe" syndrome to me.
Any time two things have even the smallest thing in common, then it's because they're connected in some way...