Isn't the problem that the customer is doing something they shouldn't / can't be doing in the first place?

I mean, hitting the volume buttons on the Sony OEM remote means they're trying to adjust the volume - but they can't do that, because the volume is fixed, so hitting those buttons does nothing when they're trying to do something. Basically, it's a visual warning that they're making a mistake.

So... seems like the answer is to just stop doing that! If the pop-up is that annoying, they're figure out to stop hitting those buttons soon enough.

Dirty hax solution: if they will never need to control the volume on the TV, pop open the oem remote and scratch off / otherwise disable the contacts on those buttons.