If he’s using them in a residential neighborhood where there aren’t any businesses which use them, you should be fine.
The museum in which I work uses walkie-talkies, for which we have a license on a public channel. Unfortunately, every now and again, young kids from around the area play with walkie-talkies and it really annoys the hell out of us, because we have to leave them at an audible volume while giving a tour of the facility. You can imagine what it’s like when there’s little boys saying naughty things for their own amusement, or intentionally messing with us while we’re trying to communicate with other staff, or trying to talk to a tour group.