«وَلَوْ تَعَافَيْتُهَا لَخَالَتْ / حَالِي وَلَمْ أَجُو مَا حَوَيْتُ»
If I had abandoned these methods, my circumstances would have been empty and I would not have gathered what I possess.
Law introduces a counterfactual condition; a lām introduces the consequence. The sound relationship between ḥālī / ḥawaytu reinforces the contrast between one’s circumstances and what one has acquired.
This is Abū Zayd’s justification, not an independent moral rule. The explanation of why he acts does not itself prove that deceiving the audience was permissible.