RealSense cameras do not need an internet connection and can be used locally offline, with processing done in the operating system of the computer that the camera is directly attached to.
You may need an internet connection to download the development kit software for the camera, but this does not require the camera to be actively streaming. If you are concerned that observe through the camera during these updates, you could put the camera face-down on a surface or cover the lens up in some way until the internet download is complete. Once the SDK software is set up on the computer, it need not be connected to the internet.
You could likely install the SDK software's installation package on a storage medium such as a USB stick and take it to an offline machine too, so that the research machines need not have an internet connection ability at all.