I don’t necessarily care if my neighbor owns an AR rifle. I do care what kind of person they are if they own one, or other firearms.
Are they one of the crowd that treats firearms with the careless disregard of a fashion accessory? Do they have to accessorized it to the utmost tacticool possible? Do they have a private arsenal? Do they leave it lying around in their home or vehicle, or any other firearm for that matter, unsecured? Do they tie guns to their personal or political identity?
All of these things are negatives of varying severity, especially any failure to secure the guns and tying gun to their identity. Why those? Guns get stolen from homes and vehicles all the time and then are used in crimes while the gun owner washes their hands of the consequences of their lazy storage. Unsecured guns are used in accidental shootings by kids or others. And identity tied to firearms is just an indication of inflexibility and possible political extremism.