My guess is that the other country is Israel.  @PhoebeRoberts suggests filing Form 8833, the instructions for which state:

Positions for which reporting is waived
include, but are not limited to, the
following. See Regulations section
301.6114-1(c) for other waivers from
reporting.
• That a treaty reduces or modifies the
taxation of income derived by an
individual from dependent personal
services, pensions, annuities, social
security, and other public pensions, as
well as income derived by artists,
athletes, students, trainees, or teachers;

--but I suppose there's no rule prohibiting its use, even if not required. Just allow some extra time for preparing the return:

Learning about the
law or the form . . . . 1 hr., 35 min.
Preparing and sending
the form to the IRS . . 1 hr., 43 min.

I would say that if the taxpayer's country of residence is obvious from the return -- in other words, they're not filing just with a US address -- then don't report the Social Security income and see what happens.  This might cause IRS to send a letter, which will take less than 3 hours for a response.  (Such letters might be sent even when the 8833 is attached.) Or they might be smart enough to know not to send such letters to taxpayers in that country, and then you can share your experience with others in the same situation.

In normal times I would suggest pointing out the problem to one of your members of Congress, and asking for advice from IRS on how to deal with it.  But of course these are not normal times.