Thank you for the question, unfortunately at the moment the plugin is not capable of this kind of filtering. Premium version lets you disable voting for specific uses roles, but this is not what you need now.
So, I think that the solution you are adopting may be the best one without modifying the plugin. I mean, showing the widget or showing only the result, depending on the current page and user.
However I’m tacking note of this need for a future update.
I am not thinking of adding an option like “people cannot vote own contents” because this plugin is intended to be as generic as possible and every content could have a different structure and checking if the current user is owner could mean different things in different scenarios, but I will add a hook filter for sure.
Thank you for your contribute.