Answer: Great question. You are correct as post-ictal agitated patients often improve over time and depending on their degree of agitation/combativeness, can often be managed non pharmacologically.
The combative patient protocol is designed to protect both the patient and paramedics from sustaining injury and so that paramedics can provide the appropriate care. If in your clinical judgment, the patient is at risk for harming themselves or others, then using midazolam for sedation would be appropriate if there are no contraindications. If however, you feel that the patient is only mild agitated and not combative, can be managed non-pharmacologically, and is not at risk for harm to self or others, then document your clinical judgment and decision.
Short answer, time is not a reversible cause and if in your clinical judgment the patient is combative and at risk for harming themselves, others or sedation is required to provide care, then proceed with your combative patient medical directive.