I am not convinced that the reports are accurate. This may be an effort to discredit Oath Keepers (OK) or conservatives in general, or it may be an error. I’ll wait for more information.
You can lawfully open carry anywhere in the state, and you can lawfully carry on private property with the owner’s permission. The police had no authority to intervene, and I suspect OK leaders knew that. There are a lot of options that could have led to this report and would not reflect badly on OK.
http://www.freerepublic.com/focus/f-news/3232129/posts?page=60#60
What about for non residents of Missouri?