I’ve seen the same thing when talking to local GIS departments in the U.S. It doesn’t matter how much the staff love using OSM and even contribute to it on their free time; the moment you bring up legalities, it goes to the legal department. The more detail you ask of the legal department, the less likely they are to say yes or even get back to you with a straight answer. On the flip side, if you ask if the data is in the public domain, that causes a lot of confusion too, because a lot of people think “public domain” just means “public”. By this reasoning, anything on Google Maps is in the public domain! 
Over the years, I’ve had more success introducing myself as an OpenStreetMap contributor and simply asking, “Are there any restrictions to reusing this data?” Some respond that there are none whatsoever, while others say no but kindly ask us to repost the disclaimer somewhere. Some express consternation that various OSM people keep asking them about the rights to the data, as if they care that much.
This doesn’t constitute legal advice, but I do think the KISS principle is worth consideration when dealing with organizations that don’t regard their data as a profit center.