That’s a reasonable point, but it relies on the assumption that Baka was talking about something that he had experience of. But the statement is a quote—a line of verse abruptly inserted in prose—and there is no reason he shouldn’t simply be repeating with strong confidence something that he has heard of but doesn’t really understand. Happens all the time.
Moreover, the central canonical example of the Brahmanical teaching on these states does exactly the same thing. Uddaka Rāmaputta propounds the dimension of neither perception nor non-perception as the goal of his teaching, but the text clearly implies that he himself had never attained that state.
Step back and look at the narrative. Baka, the stork, is being set up from the beginning—even his name—as a fall guy. From my notes:
Pali stories (Ja 38, Ja 236) tell of how the stork dozes peacefully as if meditating by the water, while in reality he is trying to fool fish into approaching so he can snatch them up. A cunning, large, white, high-flying, predatory bird who fakes meditation is a fitting image for the antagonist of this sutta.
The last thing we should expect from Baka is integrity and accuracy. He is full of ego, trying to defeat the Buddha by any means necessary, including quoting half-remembered and little-understood verses in order to one-up the person who challenges his supremacy.