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...one may postulate the Sun as a hypothetically stationary object for his thought experiment....

But Zero Sum's postulation would not "entail" that the Sun must "agree" to stand still, so to accommodate his/her thought experiment.

So what's the point of the thought experiment?

As it stands, it has no "stationary object," no anchor or criterion according to which its phenomena can be compared and judged. JMHO FWIW

Thank you so much for your insights, dearest sister in Christ!

As it stands, it has no "stationary object," no anchor or criterion according to which its phenomena can be compared and judged.

Indeed. And my objection is that the solar system should not be used to make points concerning Newtonian physics because neither the sun nor the earth nor indeed anything in the universe is stationary - and using the solar system can be misread as authentication to believe in geocentricity as merely a choice of coordinates.

Merry go rounds work as well and the point is easily made that the earth is revolving while the merry go round is spinning, that Newtonian physics are local with reference to the universe - non inertial frames invoke so called "fictitious forces."

But Zero Sum's postulation would not "entail" that the Sun must "agree" to stand still, so to accommodate his/her thought experiment.

True enough. :)

So what's the point of the thought experiment?

Pedagogy. Just like with the exercises you find in physics textbooks.

As it stands, it has no "stationary object," no anchor or criterion according to which its phenomena can be compared and judged. JMHO FWIW

When we speak of a "stationary object" it is understood that this is not because the object meets some universal standard for being "stationary" (there is none) but because the object is stationary WRT to some inertial frame. The Sun is stationary WRT an inertial frame to a close enough approximation for the purpose of emphasizing the empirical difference between a real orbit as viewed from an inertial frame and an apparent orbit due to viewing a stationary object from a rotating frame. In the context of the merry-go-round experiment, the same could be said of the "stationary" target standing still on the Earth. Does this clarify things?