You can keep bot from summoning modrod for self/mass/alt, but not pick out a single type - i.e., either the best one found gets casted, or not, for each compatible category.
Those are done by setting it to 0 in the If option in your ini, e.g.:
ModRodSelfIf=0
ModRodMassIf=0
ModRodAltIf=0
You could always delete that spell(s) out of your spellbook, I guess - and put the item in MQ2AutoDestroy to delete it if it ever shows up on cursor.
htw