[1) the delay in accepting international publishers (even with US traffic) is very odd
2) the rather large number of accounts cancelled because of international traffic. Filtering the international traffic is a burden left to webmaster, who must geo-localize their ad system. Between Yahoo Inc. and Joe Webmaster, who has the larger processing power and know how? Why can't Yahoo simply show "alternate ads" a la Adsense to international users?
Your second point here is excellent, and is one I hadn't considered. It just seems really sloppy, perhaps arrogant, or maybe plain lazy.
Why indeed can't they serve public service ads, or even optionally their own, if a click is from outside their parochial territory? I can see no good reason. To ban folks for overseas clicks is ridiculous.