Normally, Republicans strongly favor private property rights. Normally, Republicans can be expected to defer to employer policy over claims of worker rights.
But there is one set of rights that apparently trumps both private property and employer prerogatives: the right to bear arms.
In 2011, Texas governor Rick Perry signed SB 321, a law that allows employees to bring their guns with them to bring their guns with them in their cars, and to leave their guns in cars parked on employer property - even if the employer has an express no-gun policy.
Texas law continues to permit employers to bar guns from vehicles the employer actually owns, so the NRA can't claim to win them all.