Sensei's Divining Top vs. decking

[travolter]

Marek reported:

See the attached log On the last turn, opponent's library is empty (after being hit with the ultimate of Jace, Mind Sculptor). In reaction to my game-winning activation of Ajani Vengeant, AI activates Sensei's Divining Top to draw a card... and stays alive despite having an empty library.

Until Ajani resolves and kills it, that is, but still...