I don’t think anyone’s saying that. France has tasty Caribbean colonies, however.
Indeed, and the Continental Marines did invade some of the British colonies there. Likely a French flag would be no more protection.
I could see something like this happening if the Quasi-War, which IOTL went from 1798 to about 1800, exploded into a more open conflict. France would have to invade.
Having made the decision to invade, France must now ship thousands of men and ton upon ton of materials across the North Atlantic, all while keeping enough in reserve to handle any bothersome troubles stirred up by the Spanish, the Dutch, and of course the British, who are likely still smarting from the American Revolution and who wouldn't likely mind a little revenge.
Even an especially capable French general will find his mission a daunting one, invading a massive, hostile land full of armed and fiercely independent people who speak a different language, regard his very culture as foreign, have no desire to be reconquered, and are perfectly ready to fight if they must.
In addition to the difficulties of such a war, the expenditures will pile on to France's rapidly expanding national debt, already skyrocketing high ironically because of aid lent the American rebels.