Alternatively, suggest/require he (or she) pick up Broad Study (Ultimate Magic Magus Arcana that requires level 6 Magus and levels in another caster class) as the arcana allows for the magus to use spell combat, spell strike, and pretty much all other magus abilities with the spells. You still have the arcane spell failure chance from using spells that aren't learned as a Magus as well, which leads me to thinking that RAW for Magus = any spells learned before becoming a Magus cannot be cast in armor nor used with Magus abilities.
