The city of Ponca was founded in 1856 (http://www.ci.ponca.ne.us/), 23 years before the Standing Bear's court battle.  While Standing Bear is an important figure in Native American and Nebraska history, it's clear that the city was not named in honor of him, and it's a stretch to claim that the state park was either.  I presume the reason that the Game and Parks Commission mentions Standing Bear is to provide the average person with any sort of connection to a tribe they are otherwise likely to know nothing about.  If you'd like to discuss this further, please leave a message on my talk page.  –