I would like to configure the plugin to create a health result of 0% when there are any warnings whatsover, but the UI considers this an invalid situation and the plugin logic itself seems to not like this configuration.

Because the input parameters disallow entry of the count 0, and because the unhealthy threshold says "Report health as 0% when the number of issues is greater than this value." there is no possible way to define a configuration which is healthy when there are zero warnings and unhealthy for any other number of warnings.