Examples of law frequently use a past-form verb, but the text examines cases with an imperfect. Verb morphology and the temporal picture intended by the speaker need not coincide mechanically.
«لَوْ يُطِيعُكُمْ فِي كَثِيرٍ مِنَ الْأَمْرِ لَعَنِتُّمْ»
If he were to obey you in many matters, you would fall into hardship.
Here yutiʿukum is imperfect, while law still sets up the hypothetical connection. The imperfect can evoke recurrence or continuing obedience, not just one event completed in the past.