Why exactly does the brutality of the Cuban regime make it alright for the US regime to jail and persecute private American citizens who attempt to trade with people in Cuba?
That is, after all, the position of those who favor the embargo. Embargoes are not something where a magic fairy waves her wand and Cuba suddenly becomes invisible to Americans.
No, supporting an embargo means supporting the government when it fines, prosecutes, and jails peaceful citizens who attempt to engage in truly free trade. Support for an embargo also requires support for a customs bureaucracy that spies on merchants and consumers, and the whole panoply of enforcement programs necessary to punish those who run afoul of the government’s arbitrary pronouncements on what kind of trade is acceptable, and what kind is verboten. Naturally, this is all paid for by the taxpayers.