The courts will decide there's "no clearly established law".

https://www.theusconstitution.org/litigation/micah-jessop-br...

> After local police officers searched the homes and business of Micah Jessop and Brittan Ashjian, more than $100,000 in cash and $125,000 in rare coins went missing. Jessop and Ashjian sued the officers and the City of Fresno under 42 U.S.C. § 1983, a statute that authorizes damages actions against state and local officials for constitutional violations, arguing that the officers’ alleged theft violated their Fourth Amendment right to be free from “unreasonable searches and seizures.” The Ninth Circuit Court of Appeals held that under the doctrine of qualified immunity the officers cannot be sued because, according to the court, it is not “clearly established” that this type of theft violates the Fourth Amendment.

https://www.usatoday.com/story/opinion/2020/05/30/police-geo...

> For instance, last November the 6th Circuit U.S. Court of Appeals held that Tennessee cops who allowed their police dog to bite a surrendered suspect did not violate clearly established law. There, the victim cited a case where the same court earlier held that it was unconstitutional for officers to sic their dog on a suspect who had surrendered by lying on the ground with his hands to the side. That was not sufficient, the court reasoned, because the victim had not surrendered by lying down: He had surrendered by sitting on the ground and raising his hands.

To your point, law enforcement would likely side with the buyer here but the buyer isn't necessarily going to be in a position to understand that (in fact, likely the other way).