In retrospect, I should have guessed that this organization was not serious. There were glitches before I got there, such as a failure to provide directions on getting in the building, or an agenda for the day. They were also slow in responding to messages, and uninterested in my list of references.
Ultimately, this felt like an information-gathering process for them, and a day I really couldn't afford to take off for me. I was there for most of the day talking to various stakeholders, without any breaks in between.
The HR representative promised to contact me regardless of the outcome of the interview, but never did. They may legitimately have openings, but I'd proceed cautiously with this organization.