The timings don't quite add up.
JACDEC reports that the collision took place at 03:57Z (05:57L) as the 777 was taxying in. The outbound A320 wasn't due to push until 07:15L, so it seems more likely that it was the one being towed onto stand at the time.
Either that, or the time reported for the event is incorrect.
Edit: It was indeed the empty 777 that was being towed off stand, the incident took place at 07:30L, according to this report:
Deux avions d'Air France entrent en collision à Roissy-Charles-de-Gaulle - L'Express