It's pretty well established that rapid freezing promotes higher rates of ice crystal formation in living yeast cells. Regardless of food processing and rock formation. The scientific literature goes back decades with more reviews you could shake a stick at. Ice crystals are not good for living cells either. Once frozen, the yeast cells are under stresses associated with dehydration too. In fact, thawed frozen yeast are in worse shape than hydrated dry yeast. They are knackered and need to be carefully selected for post thawing. This is why my view, for home brewers generally, at least those who want to store liquid yeast strains, is shifting towards storing small aliquots of high-quality yeast in the fridge. I can't say it's a viable alternative for long-term storage over years, I'm genuinely skeptical about that. But I can say it's a better, easier option for most home brewers, at least up to about 18 months so far. I stand by my original reply to the OP, that freezing yeast cells is technically demanding involving a lot more than simply freezing tens of mls of slurry with glycerol then thawing to pitch or make a large starter. That's not sound microbiology or good brewing practice at all therefore not something I can endorse, because it's simply not something I'd do myself.
