That is illegal in the US, and the FCC's Enforcement Division eventually catches and imprisons jammer operators, and I understand even sometimes the manufacturers.
Personally, if I were at high risk of being harmed by a stalker, and the threat of an AirTag was real for my situation, I would simply ignore any such FCC law that put me at even higher risk and use a bluetooth jammer anyway. I believe in obeying the law, but with common sense being thrown in as well. Similarly, I would not chastise someone who drove 70 in a 55 zone to get a dying family member to a hospital (they should have taken an ambulance, but even if they didn't, I would not throw them to the wolves).
If it turns out enough people resort to using illegal bluetooth jammers to avoid negative consequences from Apple's AirTags, that might be time for the government to review the appropriateness of allowing Apple's technology in the first place.
I really do think that Apple has done a grave disservice to the population at large by bringing this technology to market. What was that line from Jurassic Park? "Just because you can, doesn't mean you should." I don't know what Apple was thinking. Blinded by potential profits I guess.