Why would he fake it at this time? Having been "cleared" by Banquo, who was seemingly killed by the ninjas (down to stabbing the "eye" as a detective calling card) and whose reveal I believe, Sasaki would be labelling himself as the Godfather of the ninjas (innocent result leaves only this choice). Even if he pulled it off for a while, he would eventually get lynched and lose the whole shebang.

Do you think Sasaki would rely on WIFOM for this many rounds as his only defense when he's ALREADY wandering around with an innocent result?