“Though his continuation of the custom, rather than his flouting of it, would have been more in accord with what eventually became effective hygenic practice.”
You can’t be serious. Maybe I’m reading your post wrong. Jesus did not ‘flout’ hand washing for it’s sanitary purposes - He ‘flouted’ it because the pharisees misled themselves and others into believing that man-made traditions -such as the public washing of the hands - would bring salvation to the performer of said tradition. He was, in essence, flouting ‘religion’.
But surely you know this and I’m misinterpreting your post and wasting my valuable time typing this.
At the risk of further wasting your valuable time, I’d just point out that Jesus too was a Pharisee having been ordained a rabbi through semikhah which rite was practiced only by the Pharisees at the time, and by which they later developed into the various aspects of modern Judaism, particulay Orthodoxy.
Shalom.