Yes it does, unlike before, a shits-and-giggles attacker could change all the tags in an aisle into "you're gay" without showing anything on surveillance cameras.
He wouldn't gain anything but the store would lose.
But actually: It's not that broad. It's still mostly one at a time, ish. Changing a lot of them would stand out if anyone were paying attention.
Although it could certainly be broadened...but an IR emitter that's skookum enough to reliably hit all of the shelf tags in an aisle at once would probably show up as an intensely-bright purple floodlight on the cameras. That would stand out quite a lot. :)
I don't think anyone is paying attention anywhere near enough to pick that up. Additionally, one could read some barcodes and make quite cheap battery-powered narrow beam emitters to be placed in store aimed at particular tags that would only power up once a day at a random time.
If the lulz are the point, then: Just build hide the thing in the floor-cleaning robot. Include a decent camera (they're very cheap) to catch the barcodes.
If the comms last long enough as the machine passes by to program some tags every night, then some tags get programmed every night. Nobody will pay attention to the robot's new purple floodlight in the cameras.
Shop floor cleaning robots seem to be rather clean on the outside, hard to imagine tampering with one in the field and making it inconspicuous.