II have heard Guinea Fowl are good and don't do any damage, and if you can find their eggs they can be reasonable layers.
But you can't deny they are one of (if not THE) noisiest birds there is - maybe not ideal if he has neighbours he want's to stay friends with
I've got bantams & standard chooks (free ranging in our garden) and the wee ones do just as much damage
Plan had been to move them to their fabulous new house (yeah, still
nearly finished) in the field, but given Boris & his new found liking of poultry.........
They're safer in the garden, which they've trashed (helped by the kids and endless rain we've had this year)
It's probably worth looking at having them in a run most of the time and only have them out when he's there to keep an eye on them - at least until he sees how they get on (and the plan is he'll be so in awe of how good the eggs are that he'll forgive a bit of foraging)
HTH