A far more likely possibility is that their ideology is actually centered around "Sith who happen to originate from Vega (a.k.a. α Lyrae)", not "Sith who abstain from animal products".
(A residual possibility is "Sith from Las Vegas, Nevada".)
I don't think so. The people specifically are vegan, and their leader believes that future AI overlords will punish people retroactively for their moral failings. This is reported in some of the other posts on this page.
It's wild, but a view that is is fairly widely discussed in the rationality community, but only taken seriously by Fringe groups.[1]
Apparently, being a Sith meant to Ziz that you should do whatever is in your power and desire to do, without other constraints. If you're "fundamentally good" (a thing she believes in), then what you end up doing will be a kind of maximization of good.
Of course, this is trite pulp nonsense, high-school nerd level philosophy at best.
(A residual possibility is "Sith from Las Vegas, Nevada".)