It is moot. The OEM Dunlop 220 was discontinued and is no longer available for aftermarket. The only tire "approved" or "recommended" by Honda's stickers on the bike and tire brand information in the service manual and owners manual is the OEM Bridgestone.
Is is moot but not for the reason you listed. As with any other part on the motorcycle you can use parts from other manufactures as long as they are of equal or better quality. If Honda felt that the D220 tire was sufficient and you choose to replace it with another brand it won't void the warranty. Tires are built to DOT standards. So as long as you replace the tire with one of equal or higher standard there is not a problem. If you were to replace a tire with a lower standard or improper size then there might be a problem.
Why does everyone think that motorcycles are any different than cars? Most people don't have a problem with putting different brands and even different size tires on their 4-wheel vehicles but some freak out when it comes to motorcycles. Some of those same people have no problem with running a fuel with lower octaine from what Honda specifies/recommends and don't seem to have a problem with that. Go figure.
If you could only put on what was original equipment there would be a whole lot less tire companies out there.
I think they use whatever is coming down the line. My 06 ABS came with Bridgestones, my 07 ABS came with Dunlops.
I sort of thought that as well. My '06 non-ABS came with D220's but others came with BT-020's.
I just thought of another way of looking at the issue that may help ease some minds. I'm in law enforcement. As such when I worked traffic, in California, I had the legal right to pull over any vehicle at any time for no other purpose other than to conduct a safety check of the vehicle. I never really did this but it was on the books. Back to my point. The safety check would be for things like; are the required lights on the vehicle and operational, was all the required equipment on the vehicle (muffler(s), mirrors etc.). Are the tires appropriate for the vehicle; are they the proper size and weight rating are they on an appropriate rim size for the tire. I could then let the vehicle pass if everything was in order or cite or even have the vehicle towed if it was considered unsafe for the road. What I couldn't do is cite you for having the wrong brand (manufacture) of tire on the vehicle.
The simple fact is, find a set of tires that will float your boat and let's go out and wear some tread off them!