You guys may be right. I'm not sure of the original intent of this card, and it wouldn't be the first time the Japanese was mistranslated (or needed to be clarified). Hopefully this conversation will prompt an official ruling, or get this bug added to Known Issues.
Here's the official ruling from Juniper/Sycamore:
Q. Can I play Professor Juniper if it is the only card in my hand, and then draw 7 cards?
A. Yes, you basically discard your remaining hand of zero cards, then you draw 7 cards from your deck. (Black & White FAQ; Apr 28, 2011 PUI Rules Team)
Q. Can you use Professor Juniper or Professor Sycamore with no cards in your deck, just to discard your hand?
A. No, you cannot. Discarding your hand is a cost not the effect, and you cannot play Trainer cards for no effect. (Apr 27, 2017 TPCi Rules Team)
Edited by RobRatt, 06 November 2018 - 07:05 PM.