Just a thought but has a monk tried using this drink? The Interplanar Brain Blaster might just be coded like the nec/sk spell but perhaps its coded like the monk skill, and therefore runs off the FD skill level to determine if it succeeds or fails. Very easy to test this theory out. Non-monks would almost never get a mem wipe from drinking this, but highly skilled monks would very frequently.
It wouldn't effect gameplay one way or another, but it would finally resolve the debate.