and British Columbia on my iPhone last month and the calls showed up on my AT&T bill at $0.20 per minute for BC and $0.44 per minute from the UK. Does that sound about right for international "incoming" calls? 

If you don't have any international plan, then yes I think so?
Why would he need an international plan for incoming international calls?
I think it's because regardless of whether it is incoming or outgoing, it still is international.
I think it's because regardless of whether it is incoming or outgoing, it still is international.
All incoming calls will count as minutes of use regardless of where the call comes from. In the US we do not have the calling party pays system so the user of a foreign mobile phone pays the cost of all calls made and received. On the positive side it will not cost you anything extra to call a US mobile phone number as there is no surcharge to the person who dials the call.
That doesn't seem to make sense. If they called him then they're paying for it on their end and now he's paying for it on his end too? If someone receives a call on a landline from the UK they aren't billed for the call. It merely terminated there. The person placing the calls bears the weight of the bill. If this were true, according to the per minute charges on the AT&T international country calculator, someone could slam you for as much as $5 a minute but simply misdialing to your phone.
I'm pretty sure here in the UK the caller pays for the entire call, isnt it illegal for phone companies to charge the recipient? The call-ee shouldn't pay anything. Thats what reverse charge is for.