I'd rather have him walking around with an AR than the majority of people I see handling firearms at the range.
Since when does an 18 year war vet make gun owners look bad? He's the exact person I would want walking around with an AR. I'd trust him and his gun handling skills over the majority of police.
Also, him being a war vet, his AR is not what he would see as "Heavy Fire Power". He looks at firearms differently than a regular citizen. Most troops will say it's an underpowered weapon.
If a war vet who's served 18 years isn't trusted with an AR walking with his son, who is?
The police shouldn't have taken his weapon unless they thought he had committed a felonious crime.
Also, you live in an area with no real threats that would call for an AR. Why would you walk around with one with your son? This person has a purpose for his weapon, which is hogs. I can only assume he has larger caliber firearms at home that I would deem unnecessary, he chose the correct TOOL for the job.
I walk around with a 9mm on me when I walk by myself and with my girlfriend. If I thought I may run into feral hogs I would be carrying an AR with me too, good thing I live in the city and this isn't an issue. For his area I would deem his weapon necessary.