look at the change that happens with the two cowherd similes before first jhana, and the description of the ekodi samadhi before and after. Before, it doesn’t have passadhi. After, it has passadhi. Passadhi is passadhi-sambojjhanga, in particular the kaya-passadhi.
Nothing about the fundamental nature of vitakka has changed. Only the energetic intensity and frequency of it. If it did undergo a shift into something else, this is the time for the Buddha to explain it. He doesn’t. In the agama parallel, it’s even more explicit and unambiguous by completely removing the first jhana formula.
It’s only because you were indoctrinated with wrong ideas from Vism. and Ajahn Brahm that you have trouble reading and interpreting the EBT. You have to clear your mind, and read the EBT without bias and preconceived ideas and then the obvious will hit you.
This also matches actual experience. Second jhana energetically feels exactly like the simile in AN 5.28, like you’re completely suffused with water but you feel the powerful vibrations from your spine to your head bubbling in your tailbone from the spring feeding the lake. It has a feeling of continuous orgasmic full body bliss.
From second jhana, experiment with V&V, thinking and pondering, and then you will know from experience exactly just how much kusala and akusala ordinary thinking and evaluation you can do from that state without reducing the full power of the whole body orgasmic bliss.
Even from an arupa samadhi, where you can’t find your body at all or feel any mosquito bites and leg pain, you can do perfectly ordinary V&V thinking and evaluation.