The obvious answer is if you're bothered by this is a DDOS attack. Flood the system with innocuous reports, preferably ones that have some superficial plausibility.
The downside is that AFAIK, there's not much of a mechanism to embarrass Walmart or DHS specifically, and local LEA's (with lots of legitimate duties) would be taking it on the chin to make this point.
Propaganda-based security encouragement to be vigilant is just more security theater anyway. Such messages just blend into the background noise of life too quickly to have any real impact IMO. Human nature being what it is, I see these as being about as effective as speed limit signs on the freeways after a month, if not less.
In theory at least, does not everyone already "know" they're supposed to notice suspicious/criminal activity and say something? It's kind of like a campaign to encourage proper wiping in the bathroom. Either you already do, or...
Designating specific people as "observers" or nosy old ladies as "block captains" with an actual defined reporting structure to DHS or something, then I'll be concerned.
