Here he's working with both the A-sharp, which is unambiguous, and the D-sharp, which navigates a Didymic comma.
Esu: So 'Trane is thinking the note is D-sharp? And is avoiding the comma?
A: I don't think he's consciously avoiding the comma, and I think he knows it's D-sharp but doesn't really care.
This is the lowest point we go to; we climb all the way back up, past G major, back to B major, and then even up higher, all the way to D-sharp major.
If we conflate the B and C-flat, and the E-flat and D-sharp, it suggests that the Diesis is important, that we have some kind of virtual return, and that is exactly what the piece scrupulously avoids.