You make the call

[Atl Blue]

You say that once R1 legally occupies second base he can not be forced to advance.

Correct.

But later you say that if R2 acquires third base, he can be "forced" to retreat if the force out is removed because R1 was put out.

I don't like the term "forced" to retreat, because "forced" has a specific definition in baseball. But the actions of his teammate R3 legally returning to 3B will now "require" him to leave the base, yes.

So R2 legally acquires third base. Then because R1 is out, the is no longer legally on the base?

If you mean R2 in place of "the", then yes, that is exactly right.

If this situation ever comes up, just call R1 and R3 out.

I see you are part of the "order of the tags crap doesn't make a difference" camp, led by Windy. By the rules (7.03 and 7.08e), you would be incorrect.

Who cares about what the order of the tags were?

As I said earlier, this is a bizarre case play that would never happen. It was written to show how to deduce certain solutions from the rules. It was typical of a question you might see on a test. If this is your answer, you failed.

Everyone konws that only 1 runner can be on a base, therefore no one will complain when you call R1 and R3 out.

Actually, if I were the coach, I might, depending on the speed and ability of the specific runners, and if you got it wrong. And if you don't pay attention to the order of the tags, you MIGHT get it wrong.

Besides, I assume the third base coach will already have his hands full yelling at the runners,

You are totally correct about that!

he will have no time to question your call.

Funny, they always find time to do that. And many coaches will think this whole mess is somehow the ump's fault, too!