I'm not an expert on WildType's specific process, but I've read that while mammalian cells need to be grown at ~37 C 5% CO2, fish cells can be grown at lower temps due to differences in biology. I just read a paper where salmon cells were incubated at 13 C and 3% CO2. Could be that they're expecting energy cost savings with no need to pre-warm media, heat bioreactor, etc., but it's also possible that cooling will be necessary (depending on the location of the plant) or that mammalian metabolism will produce enough heat that bioreactor heating may not be an issue. I think the jury is still out on that. So maybe they just looked at where they could find their niche in a market with lots of pork, beef, and poultry companies already? Or maybe the founders really cared about marine ecosystems?