It doesn't make much sense.

When a high court makes a decision, all the lower courts need to follow it. If a high court says anyone on trial for murder must be tried as an adult, then all the lower courts need to follow that rule. It is incredibly rare for a high court to make such a broad rule though. Usually their rulings are much more precise. Like: on trial for murder, over the age of 15 and shows at least 4 of the following 12 signs of maturity: has a job, has a driver's licence, etc...

This was a case where their ruling was incredibly broad and had no conditions. They literally said "we are adding 'frozen embryo' to the legal definition of 'child'" and just left it at that. This means all courts in Alabama must consider frozen embryos to be children when ruling on cases, which of course has a lot of practical problems.

Already people have pointed out that in vitro fertilization has effectively been banned. All IVF clinics in Alabama are currently closed. Republican law makers cheered this until it was pointed out that IVF clinics create babies. They aren't abortion clinics. Now they're scrambling to re-legalize IVF in Alabama. So yeah, all the old men in Alabama have zero clue about what they're doing. They just like ensuring everything is considered a child because that's what Jesus wants.