I presume your point is that until the "revolution" is over, then the British were still not "foreigners." Your point is wrong as a matter of law and the fact you use to support that point does not support it in any event.
As to your point itself, the Declaration of Independence quite succintly refutes it by its statement that "these United Colonies are . . . Free and Independent States" (I've highlighted the money part of the quote):
"We, therefore, the Representatives of the united States of America, in General Congress, Assembled, appealing to the Supreme Judge of the world for the rectitude of our intentions, do, in the Name, and by Authority of the good People of these Colonies, solemnly publish and declare, That these United Colonies are, and of Right ought to be Free and Independent States; that they are Absolved from all Allegiance to the British Crown, and that all political connection between them and the State of Great Britain, is and ought to be totally dissolved; and that as Free and Independent States, they have full Power to levy War, conclude Peace, contract Alliances, establish Commerce, and to do all other Acts and Things which Independent States may of right do. And for the support of this Declaration, with a firm reliance on the protection of divine Providence, we mutually pledge to each other our Lives, our Fortunes and our sacred Honor." (hyperlink to full text).
In other words, from that moment that document was signed onwards, British were a foreign presence in America. The Revolutionary War had yet to be won, true, but a new country certainly was born on July 4, 1776. Technically speaking, the correct term for the Revolutionary War is the "War of Independence" by the way. Only if the United States lost that war could the moniker "Revolutionary War" be applied to it.
As to the fact that you cite as supposed support for your point -- namely, the final ratification of the U.S. Constitution in 1789 was the ending of the "revolution" and thus the moment in time when British citizens first acquired the status of "foreigner" whilst in America -- it does not even support your thesis. First, the Constitution is an organization charter of the present United States government. There have been at least two other U.S. governments besides the present one, the one between July 4, 1776 and the effective date of the Articles of Confederation (March 1, 1781), and the one while the Articles of Confederation was in force (1781 to 1789). What aspect of the present U.S. Constitution ended the "revolution" that the Articles of Conferation did not?
Moreover, Britain itself recognized the United States as a separate country in 1783 when it signed the Treaty of Paris. An argument could be made that Britain itself recognized the United States even earlier, in 1781 when Washington defeated Cornwallis at Yorktown or in 1782 when the Preliminary Articles Of Peace was signed. What aspect of the U.S. Constitution in 1789 somehow added to the fact that Britain itself recognized it was a "foreign" entity vis-a-vis the United States at least six years earlier?
Sorry for the history lesson so early on a Sunday morning but facts are facts, facts are important, and precision in argument requires that facts be used correctly.