Nope. What he would do is play the Juniper discard his hand then draw the last 2 cards then go from there however unless (s)he has a way to get cards back in his/her deck before the start of His/Her turn. If the Player does not get any cards back in the deck by the start of His/Her next turn then that is considered a loss.
for Example:
I playing you.
I have 2 cards left in my deck I play Professor Juniper. I then Discard my Hand then draw the Final two cards if I do not have a way to get cards back in my deck and I attack(excluding deck and cover)/pass. Then it is your turn.
You do what you need to do to try to win the game. (or just draw then pass for Spirit of the game)
I have no cards left in My deck and I am unable to draw at the Beginning of my turn. Therefore you are declared the winner.
So to be clear, you don't official deck out until you attempt your mandatory draw for the turn and find no cards left. This can be pretty important since it gives a period of time to replenish the deck.