I told myself I wouldn’t do it but I did the research: turns out there’s one company who claims to brew with “donor” yeast and that’s the company she’s talking about partnering with. As far as I can tell from everything I’ve found reporting on them these claims are unverified so everything below should be taken with a large amount of skepticism.
Their websites are pretty sparse with information (and unsurprisingly creepily neckbeardy) but looking at what’s available and been reported I’ve been able to piece together what I think is happening. They talk around it and try to couch it in scientific jargon, it sounds like they’re using it to produce lactic acid only, so no alcohol, which is then sterilised and filtered to death before being used as an additive.
All in all it seems that the steps they describe between “donor” and beer that would result in no actual yeasts from the “donor” in the beer at any point, or even any yeasts cultivated from the originals - Which would seem to be the ultimate intent, probably for food safety law complaince. And this all assumes that they aren’t just lieing about it.