In Brown Transport Corp. v. NLRB, 334 F.2d 30 (5th Cir. 1964), in which the picket signs made clear that picketing was directed only to the employees of the primary employer and no one else, see id. at 31, the court held that "[t]here is simply no excuse for picketing where the message is seen by neutral employees of neutral employers but is not seen at all by the employees of the primary employer," id. at 39.