“Go forth, light or heavy” (al-Tawbah 9:41) strongly urges mobilization. Other passages recognize legitimate disability, illness, and relevant exceptions.
The question is whether the exhortation requires every person to mobilize under every conceivable circumstance or whether the duty is understood within ability, legitimate excuse, and the character of the undertaking.
An exception for someone unable to participate does not necessarily cancel the larger command. General exhortation and lawful exemption can coexist once the intended scope is identified.