S. R. Faruqi:

The point is that because of weakness and wretchedness we weren't even able to writhe around properly, and the Hunter's blow was so powerful that the moment we came into the net, we gave up our life.

Ghalib has, in a Persian verse, well versified the opposite face of this theme:

'At the time of slaughter, to writhe in a state of self-lessness is my sin
But to deliberately not make the dagger sharp-- whose sin is that?'

FWP:

SETS == BHI; WORDPLAY
MOTIFS
NAMES
TERMS

Here's again the 'passive of impossibility' as one option, and the regular passive as another; for more on this see {66,1}.

The word zabūñ (see the definition above) has both a morally neutral sense ('weak, infirm, helpless, unlucky') and a negatively charged sense ('vile, evil, ill, faulty'). In either case, such an 'unworthy' prey might be one whom the Hunter wouldn't bother about at all, even to the extent of putting him out of his misery by killing him quickly (and thus causing him to 'mingle with the dust'). Or it could be that the prey himself unfortunately wasn't able to die quickly, or to kill himself, and thus to 'mingle with the dust'. (See the definition of ḳhāk meñ milānā above.)

SRF reads the idiom ḳhāk meñ milānā as meaning something like 'to writhe on the ground with grief'; on this view, the speaker's wretchedness is caused by the fact that he did die all too quickly, and thus was unable to give proper vent to his grief by a prolonged physical show of grief and sorrow. This interpretation also goes nicely with the alternative reading of malānā , 'to cause to rub' (see the definition above); since the relevant diacritics that would distinguish the two short vowels haven't been provided, this alternative can hardly help but hover in our minds, for the speaker also wasn't able to fling dust onto his head, in another traditional sign of grief-- or perhaps wasn't able to rub his whole body with dust, or roll around and 'grind' the dust into his body in an even more extravagant display of sorrow.

And then, there's one more enjoyable touch. The lover's one great goal is to 'join', to be 'united with' [milnā] the beloved. Not only has this supreme joy not been vouchsafed to him-- but he hasn't even been able to 'join', to be 'united with', the dust. You'd think that someone who missed out on his first choice might have better luck with his fallback position. But no: the lover hasn't had any kind of milnā whatsoever. And because of his weakness or wretchedness, he hasn't had any choice in the matter at all. He's always been moved around by others: even his lack of milnā is entirely in the passive of the causative [milāyā jānā]. No death (or a too-quick death), no opportunity to grieve, no chance at all of anything else-- how zabūñ can the wretched lover become?