Your quote is good, but only on the surface.
There are two types: those that habitually dwell and those that do not habitually dwell.
It never said (and it would), those that can attain and those that cannot.
These were special circumstances, and remember it is an arahant that was showing vitakka (almost impossible in normal circumstances).
Look at your last line (using Pitaka trans):
taṃ vitakkentoti ‘‘sāmaṇerassa senāsanaṃ natthi, araññañca sīhādīhi saparissayaṃ, kiṃ nu kho tassa bhavissatī’’ti taṃ vitakkento.
Thinking about him means thinking: “The sāmaṇera has no dwelling, and the forest is dangerous with lions and so on, what will become of him?”
evarūpoti ediso yathāvuttasāmaṇerasadiso khīṇāsavo.
Such a one means an arahant similar to the sāmaṇera mentioned.
ime dhammeti imasmiṃ sutte āgate sīlādidhamme.
These Dhammas refers to the Dhammas beginning with virtue (sīla) mentioned in this sutta.
āvajjitvāvāti attano parisuddhasīlatādiāvajjanahetu eva samāpajjituṃ sakkhissati.
By reflecting means he will be able to attain by merely reflecting on his own purity of virtue and so on.
This line here:
By reflecting means he will be able to attain by merely reflecting on his own purity of virtue and so on
It is easy once these very odd obstacles are removed for the arahant. Surely you agree that these are odd circumstances for an arahant. It is only based on his duty as a preceptor that he would have these kiriya thoughts circling in his mind. Once it stops, he merely needs to reflect. While in other situations, we can say the hindrances are temporarily suppressed in mundane jhāna, it was this odd situation which his attainment was temporarily suppressed.