You are confusing food & medicine sales, which are basically for humanitarian reasons, with ability of PRIVATE businesses to trade with Cuba. Corporations from USA can not set up factories in Cuba, or import Cuban goods for sale in USA. Not even Cuban cigars!
Every foreign corporation that invested in Cuba under Castro were screwed by the Cuban government. It is masochism for American business men to invest in Cuba, even if it were legal, to follow the path of all other foreign investors. All assets of American corporation operating in Cuba were confiscated without compensation by Castro’s Stalinist regimen at the beginning of the revolution. Fool me once, shame on you; fool me twice, shame on me. The big losers in the Castro/Obama/Francis pact, the oppressed Cuban people and the American taxpayers. The winners the torturers of the Cuban people whose decayed regimen is going to be kept afloat by the largesse of comrade Obama.