1. It isn’t known how the stem cells will be derived, or what sort of nutrient will be used to grow the “meat.”
2. Many people hold by rennet from meat, and some even allow it from a treff animal – and some people insist on vegetarian rennet. It’s an ongoing dispute. Anyone who believes this is a settled manner is in error.
3. The original wild Turkeys, which in no way resembled modern Turkeys (they fly, feed themselves and are quite wild) were not universally accepted in the early 16th century and there was much discussion (so amusing, as many thought they came from India and were a type of chicken). It was no slam dunk they would be accepted. Over time a consensus was reached, but one finds discussions and debates lasting until quite recently.