The two words to pay attention to are
- sankappa (resolve or thinking), and
- jhāyati (verb for “doing jhāna”).
Both Ven.'s translate “doing jhāna” here as “brooding”. But the point here is the nature of first jhana’s V&V (vitakka & vicara) is ordinary type of thinking. If the thinking is about a wholesome topic, like 4bv (brahmavihara) or wholesome Dhamma teaching, then it’s first jhana provided you can simultaneously maintain passadhi-sambojjhanga (pacification of body and mind, to the point piti-sukha manifests).
Here in KN Snp 4.7, it’s a wrong first jhāna based on 5 hindrances, specifically lustful resolves/thinking.
See these passsages for more info on wrong jhāna:
MN 36 austerity of holding the breath “jhāna” wrong jhāna, paj-jhāyanti nij-jhāyanti avaj-jhāyanti AN 6.46 dhamma teachers disparaging meditation experts AN 11.9 simile of horse who only thinks about eating MN 108 praisworthy jhāna and un-worthy MN 50 insult monk’s jhāna by comparing to animals hunting KN Snp 5.0 vatthu-gāthā (prologue-verses)
KN Snp 4.7 tissa-metteyya (To Tissa-metteyya)
(excerpt, from Thanissaro trans.)
♦ “yaso kitti ca yā pubbe,
|His earlier honor & dignity:|
hāyate vāpi tassa sā.
♦ etampi disvā sikkhetha,
|he should train himself|
|to abandon sexual intercourse.|
♦ “ saṅkappehi pareto so,
|Overcome by resolves,|
kapaṇo viya jhāyati.
♦ sutvā paresaṃ nigghosaṃ,
|like a miserable wretch.|
maṅku hoti tathāvidho.
|Hearing the scorn of others,|
Here’s Bodhi’s translation of the same passage, with NIddesa cmy.
(b. bodhi trans.)
817. “Whatever fame and acclaim he previously enjoyed,
these fall away from him.
Having seen this, one should train
to abandon sexual intercourse. (4)
- “Oppressed by his thoughts,
he broods like a poor wretch.
Having heard the reprimand of others,
one such as this is humiliated. (5)
(Niddesa cmy on that verse, B.Bodhi KN Snp trans.)
818. For one who does not abandon sexual intercourse,  oppressed by his thoughts . . . is humiliated. The reprimand of others: words of blame from his preceptor and others. Humiliated: discomfited.
Nidd I 109–10. Oppressed by his thoughts, he broods like a poor wretch: Troubled, oppressed, weighed down, pursued, and closed in by sensual thought, malevolent thought, aggressive thought, and thought of views, like a poor wretch, like a dullard, like a stupid person he meditates, premeditates, out-meditates, and mismeditates. Just as an owl on a branch waiting for a mouse meditates, premeditates, out-meditates, and mismeditates, or just as a jackal on a riverbank waiting for fish meditates, premeditates, out-meditates, and mismeditates, or just as a cat waiting for a mouse by an alley or drain or rubbish bin meditates, premeditates, out-meditates, and mismeditates, or just as a donkey unladen, standing by a door-post or a dust-bin or a drain, meditates, premeditates, out-meditates, and mismeditates (see MN I 334,18–34), so the one who leaves the homeless life meditates, premeditates, out-meditates, and mismeditates like a poor wretch, like a dullard, like a stupid person — troubled, oppressed, weighed down, pursued, and closed in by sensual thought, malevolent thought, aggressive thought, and thought of views.
NIddesa seems to take a point of view it’s an unpleasant wrong jhana experience, but it can be very pleasurable.
Somebody who is jhāna capable can easily do evil/wrong jhāna by taking an unwholesome object, such as eating delicious food, sexual fantasy, tantric sex with wrong piti-sukha lasting hours, etc.
conclusionThe point is people need to wake up to the reality that Jhāna doesn't just mean 4 jhānas, right samādhi, or right jhāna. The word jhāna or doing jhāna (jhāyati) is also used to describe ineffective or wrong jhānas, such as the Buddha holding his breath for 10 minutes as an austerity, or a cat in samadhi hunting a mouse.
This shows for sankappa, V&V (vitakka & vicara) to remain coherent through all of these usages of “jhāna” in the suttas, it must mean “thinking and evaluation”, not “placing the mind and keeping it connected”.