A previous poster had the right idea...concealed, low profile, ignore the signs. Worst case scenario you'll be asked to leave. Probably not a good idea to do that in a Post Office, though.
Bob
No, the previous poster was entirely wrong. This isn't a debate on concealed carry vs. open carry (i.e. the "concealed means concealed" ******). This is an issue of our 2nd amendment rights.
The OP is entirely correct in his assessment. He won't shop there and he's going to push it with corporate and let them know what the consequences of the "target rich" environment are. As well he should. As well we all should. Starve them out of business or change their minds, their choice.