Being everywhere in the universe at the same time opens up pretty big possibilities.
Paris could have brought back a virus he picked up from phenomena that Federation would begin to dream of for the next thousand years.
Or simply could have been in a part of space that affects Human physiology in the way it did with him.
Coupled with effect of infinite velocity, it's possible this interaction and a combination of factors was precipitated in Paris 'evolving'.
TW as the Borg use it is actually quite similar to the QS technology as it was explained on-screen.
I would surmise BOTH are aspect that remove a ship from being able to interact with the known universe as Warp would allow.
TW that was achieved by Paris is a completely different beast apparently that the Borg never achieved.
And it's possible that the Voy and later on SF adopted a different explanation for what TW stands for.