I don't know if a gray rectangle is meaningful.
The idea is to have something unobtrusive when the USB remote is not enabled. Rather than have nothing there (as it currently works), I think that the grey box tells you it's "off" while not being too distracting. If you don't know what the grey box means then you probably also don't know about the USB remote and so won't care?
This may come down to personal taste and preference. Its not important enough for me to argue about - just brainstorming ideas here.
The proposed text display is for me very intuitive. I see immediately which status the USB port has.
It took me a few seconds to figure out that
USB:rc means "remote connected" and
USB:comm means "USB available for ptp communications".
REMOTE:ON &
REMOTE:OFF might be better? Especially if the patch I'm working on to allow the battery temperature sensor input to be the remote trigger gets accepted.