That’s a complicated legal question the courts will have to answer.
The closest analogy I can think of is Wisconsin’s margarine ban in effect from 1895 to 1967 (see story here); as far as I know, it was never struck down by the courts.
That ban was enacted to protect Wisconsin’s dairy farmers from competition by cheaper margarine. It also had the effect of pushing a less-healthy product on consumers (see Mayo Clinic’s evaluation of butter vs. margarine here; the difference is butter has saturated fats, versus margarine’s unsaturated fats).
It was widely evaded by consumers who flocked to the state line margarine stands and smuggled it home, mostly because it was cheaper. Single-earner families with lots of children were prevalent in those days, and average families couldn’t afford to feed their children butter.
Florida’s and Alabama’s motivations for banning lab-grown meat (photo, above; see story here) are similar: Protecting their farmers from competition by cultured meat (which isn’t the same as plant-based meat substitutes; it’s actual meat, but is grown in tanks from cells instead of harvested from living animals, see story here).
I don’t know whether cultured meat is cheaper than farm-raised meat. The product is so new the medical community doesn’t seem to have an opinion yet on whether it’s healthier (see story here), but the FDA has no health concerns with it (see story here). The main benefits touted by promoters is it’s less cruel to animals and better for the environment.
Doctors discourage eating red meat (beef and pork) because it’s unhealthy for the heart and contributes to obesity. The cruelty of slaughterhouses is no secret, but most consumers ignore it, and only care about price. Livestock, especially cattle, contribute to global warming because they emit copious amounts of methane (read article here).
People who are health conscious and care about the environment are not, generally speaking, meat consumers. If they eat meat at all, it’s likely to be fish and/or chicken. They may consume plant-based meats, or be vegans. The market for lab-grown meat, if there is one, more likely will be people presently consuming farm-raised meat.
Getting back to the laws banning cultured meat, aside from questions of legality, this is butter-style protectionism pure and simple. America’s economic system is based on free markets and competition, and this is government interference in markets to prevent competition in order to favor a particular group of producers.
Just to be clear, these are Republican laws. Republicans also were behind so-called “ag-gag” laws that made it a crime to photograph or video cruel or abusive treatment of farm animals. Those laws were struck down as First Amendment violations; the cultured-meat ban potentially could run afoul of the Commerce Clause, but that’s less clearcut.
This is a case of political expediency trumping ideological principles. Here, Republican politicians are abandoning their free-market principles to protect farmers, an important GOPO voting constituency, from competition by non-farm food products. Just as was the case with Wisconsin’s now-rescinded margarine ban.
Such bans attempt to force consumers to buy products when they prefer something else. That’s not the American Way. It’s not free-market economics. It’s politics. Do you want politicians deciding what you can eat, when their goal is not your well-being, but someone’s profits? This is margarine economics all over again.