Validation ignored outside of Views preview?

My customer wants to be able to update a content type display page of fields.
I see that Display Suites would invoke the Drupal Display in conjunction with Views could let her do this.
However, they have lots of historical SEO data in the form of "/doctor/dr-foo/" and have Alias pattern to match node/x to this pattern.
That's background that may be helpful in context.
So with module to plug into Views, I have set up a Validation rule to capture the second argument to convert the 'dr-foo' alias to a node ID. I can see that in View Preview that it does work.

But saving it, and viewing in outside of Views returns the result as if the filter value is NOT in the url.
Inside Views, I've placed a breakpoint inside the views_plugin_argument_validate_url_path.inc and see the function works properly. Outside of Views, this plugin is not triggered, but seemingly ignored.

This is probably a misunderstanding of the Views module itself, but I'm unsure why the plugin is not at least invoked in this View outside of the edit screens for it? thx, sam