Indeed. It can´t be stressed enough that jihads are ALWAYS a defensive 'last option' reaction to foreign invasion/occupation of muslim territory. A (holy) war initiated against a non-muslim area can NEVER be a proper Jihad.
Also speaking of Spain their should be animosity between the Muslims in Iberia and those in Northern Africa because historically the main reason why Iberia ended up as christian was because muslims outside of Iberia didn´t want to get involved there.
It has to be noted that under the Umayyad Caliphate aggresive Jihading was very much the order of the day. According to what i have read, it was even so central that peace with infidels where not allowed and respites from the fighting were seen as cease-fires basically. So the concept of Jihad was never statically defensive of nature. But once continous expansion stopped and the Abbasid Caliphate succeeded the Umayyad, the notion of constant offensive religious warfare was eventually dropped completely, so as when the crusades came along the Jihads were now solely defensive of nature.
So for our period, yes, i think it might be a good idea of a historical accurate representation of the concept. But it might end up nerfing the muslims too much, so i don't know if it is a good idea gameplay-wise.