If you're going around rubbing all the leaves anyway, you may as well just squeeze a little harder to squish all the aphids to death. More will come regardless of whether you use rubbing alcohol or squish them.
The isopropyl will evaporate but the additives won't. In the US, by law, all rubbing alcohols must have additives added to make it poisonous. Even ...
Isopropyl alcohol acts as a desiccant and melts the wax that is some insects bodies.
It also evaporates so very little remains. It is not absorbed by the plant and washing with water after you harvest is recommended anyway.