Second-generation jackalope retainer

Megan Wallent and family have been vacationing in France, and in their hotel bathroom they found this, um, piece of equipment:

I have no idea what this contraption might be. She says that it looks like the vertical arm should pivot downward through an arc of however many degrees, but it doesn't actually move. As close as I ever came to a French rest room was a tuvalet in Istanbul's (not Constantinople's) Atatürk International Airport, then known as Yeşilköy Airport, which had signage in Turkish and French, and my French at the time was less pathetic than my Turkish; apart from the fact that I remember nothing about it, I can't really offer any suggestions. One commenter at Megan's site reckoned that it might be a support for wheelchair users to facilitate movement off and on the pot, as it were; this seems at least plausible, anyway.