People wear more than one hat. Your guy was a Senator but is also a Filmmaker and a Homeschooler. I say open it up to everyone, but be very skeptical of full-term Governors. For me, I just rule them out as a first-order sort algorithm.
But why so easy to support a first term Senator? I know that some don’t think experience matters but I do think it does matter. Obama has been a train wreck due to his inexperience. If he were experienced, we’d be dead right now.