A primer on understanding eye-witness, body-witness, and when we can treat "eye" and "body" as metaphorical or literal

kāya-sakkhī: body witness

kāya-sakkhī, kāyena phusitvā = eyewitness, body witness

✅ kāya-sakkhī = eyewitness, body witness. 'Body' here can be both literal and figurative, sometimes only figurative.
✅ kāyena phusitvā = eyewitness, literally contacted with the 'body'. 'Body' here can be both literal and figurative, sometimes only figurative.
⛔ 4 jhānas are part of 8 vimokkhas, part of 8 abhi-bh-āyatanas, part of 9 meditative attainments.
They are part of those groups, not equivalent to them.
So you can not say because formless attainments are also part of 8 vimokkhas,
and formless has a figurative mind only 'body',
therefore 4 jhānas must have a formless mind only 'kāya'.
That's fallacious. It would be like saying, Australia was a British penal colony where they sent their criminals,
and since John Doe is Australian, therefore John Doe is a criminal.

Very short article, a simile to help you get a feel for the type of fallacious reasoning Sujato uses in 3rd jhāna by wrongly applying a context for which it doesn't qualify: 

Sujato and his famous friends get into all the V.I.P. rooms in the hottest spots in town, anywhere in the world

Very short article, this simile shows the fallacy of Sujato taking a narrow interpretation of eye-witness to either be only literal or metaphorical:

eye-witness at 9 summer parties complex: How some body becomes a mind only 'body'

Am I a miracle worker more brilliant than the Buddha, or did Sujato erroneously misinterpret kāya here?

DN 2: I perform a miracle, B. Sujato claims Buddha had an impoverished language and was forced to redefine 'body' as 'mind'

quoting passage where Sujato explains the rationalization of his 3rd jhāna interpretation

B. Sujato third jhāna, "The body as metaphor", more like out of context, out of his body, out of his mind