In credit to the BoF1 Magic Argument, it DOES hit magic defense in game, just BoF1 has a really screwed up Magic Defense system (Magic Defense only applies when you use Defend and/or Shield, where the damage reduction is affected by the character's Magic Defense score.)
Though, I think an odd parallel to this scenario, odd cause the series is so fucked up in this regard, is SMT Null Magic.
I seem to recall that Null/Reflect/Absorb Magic in Persona 2 hits many Set Damage Moves like Heiros Glupaine, cause they are technically magical, yet they ignore magic defense and what not, or heck, the character's stats in general. However, it still rams into Magic Immunity. Why should Frog Drop vs. Worker 8's Magic Immunity be any different?