Can you do an ashi-waza without a grip on your opponent and score an Ippon? Apparently so, according to the IJF Referee Commission. They say that when a throw is successfully executed, resulting in a nice, clean throw onto Uke's back, it is Ippon even if Tori does not have a grip.
Ezio Gamba questions this. He says that since Blue has no grip at all when executing the throw, it should be no score.
Juan Barcos says in some cases, no grip can also result in Ippon. Vladimir Barta says it's instructive to look at how Uke reacts. Uke accepts that he was thrown.
Gamba maintains that it should be no score because there was no grip. Barcos reiterates that sometimes a "no grip" throw can result in Ippon.