A scholarly question here concerns how far the indirect implication depends on using a past form. If the form were changed, would all allusion disappear? Merely counting verb forms does not resolve this.
Taʿrid depends on the contextual indication that an apparently directed statement also conveys a lesson to another audience. The relevant objections separate the function of morphology from the function of the entire context.
Thus distinguish a particular rhetorical benefit of a past form from the broader operation of indirect implication through the utterance as a whole.