The next discussion treats shedding tears as a possible allusive sign. A chain can move from tears to grief, from grief to separation, and thence by further inference to a desired reunion or joy.
جَعَلَ سَكْبَ الدُّمُوعِ كِنَايَةً
He treated the shedding of tears as an allusion.
Tears are not an unequivocal sign of one emotional state; people may weep from joy as well. When the intended conclusion depends on several poorly indicated intermediates, the metaphorical transition becomes burdensome.
The objection concerns the clarity of the inferential route, not the legitimacy of discussing emotions in poetry.