Inflict Light Wounds allows the caster to touch a creature and deal 1d8+1/CL (max +5) damage. pH unbalanced, are you really arguing that a potion of inflict light wounds would give the drinker the ability to make that touch attack?
Nope. After sleeping on it, I came to the same conclusion -- and Inflict Light Wounds was the exact spell I used to work through it.
Honestly, if it had been any spell other than Frostbite I wouldn't have blinked twice, but the multiple charge property Frostbite has makes the interaction seem very strange to me.
Having said that, I still seem to remember there being a clause about a caster being able to choose whether or not to discharge a touch spell on themselves. Is that right, or am I misremembering? If so, what I would do is give the imbiber a choice as to whether or not a touch spell affected them -- with the spell fizzling if it didn't.