Caring whatsoever about overseas piracy would imply he acknowledges the existence of a significant playerbase overseas. If he acknowledged the existence of a significant playerbase and cared about piracy overseas, the logical approach would be to facilitate distribution to those areas. However, ZUN acknowledges there is a fanbase overseas, but doesn't really attempt to ease distribution overseas. Ergo, he either doesn't find the playerbase significant, or he doesn't care much about overseas piracy. So, people are likely to pirate his works. However, this does not make pirating his works acceptable nor validate people's reasons for it. Either way, please refrain from talking about pirating his games, as it is against the forum rules.
The true point is, if you care enough about how much ZUN cares about people pirating his works, you buy them regardless of what ZUN thinks.