Similarly, you can eliminate the [word] ‘rational’ from almost any sentence [you utter]. [Saying] “It’s rational to believe the sky is blue”, [saying] “It’s true that the sky is blue”, and [saying] “The sky is blue”, all convey exactly the same information about what color you think the sky is—no more, no less.
As you pointed out, the first sentence is not logically equivalent to the second and third (the second and third are logically equivalent according to Tarski’s semantic theory of truth).
I think the intended meaning is as follows:
As you pointed out, the first sentence is not logically equivalent to the second and third (the second and third are logically equivalent according to Tarski’s semantic theory of truth).