1) This looks like an overreach by the police, and one that is not atypical of some of them. If I were in a position to help, I’d be sending a lawyer down there to review their procedures, clarify the law with them – and make sure the guy gets his guns back, pronto.
2) On the other hand, taking a hike in rural Texas with a rifle slung over your shoulder because of feral pigs and cougars and such looks like sheer dumb@ssery to me. I have almost 1,500 miles of hiking and backpacking experience and I’ve camped amidst grizzly bears and baboons, and I never thought I needed a gun for protection. To take a hike with your son while armed is your right, of course, and that right needs to be protected. But you look stupid doing it. The guy already had a concealed-carry permit; the rifle is just a fashion accessory.
3) The son was working on Hiking Merit Badge. I am a counselor for said badge, as well as a former BSA Camp Director. As a father-son activity that fulfills a Merit Badge requirement, hiking with a rifle is fine, I suppose, just like walking to your deer stand would be; however, if more than just family were involved – if this were a “Scouting event” that required two-deep leadership and the filing of a Tour Plan, etc. – then it should be noted that carrying a firearm along on a hike is probably a violation of BSA rules as expressed in both The Guide to Safe Scouting and the Shooting Sports manual of the BSA National Camping Schools. If I were that family’s Council Scout Executive, I’d be quietly ascertaining what was going on and reviewing policies with Council volunteers.