I agree that Whataburger should post like H.E.B. does. I remember when they announced their policy as telling people they would not be allowed to carry and it made no sense to me. The only possibility I came up with is that the announcement was made to quiet down anti-gunners and they planned to let it go without enforcement and just dying out quietly. The problem is this is not the first time Whataburger has had this exact same problem and reiterated their policy.
Post it or drop it would be my advice/request.