The creator is not personally opposed to foreigners playing his game, and actually took some flak from other Japanese for keeping it open (from what I've heard anyway), but one of the conditions he has mentioned for his game is that he does not want his work reuploaded. This is pretty much a constant rule among all small individual developers, so it's not like he's just doing this to be a jerk.
One of the big problems for developers to have their work reuploaded, esepcially in places on the net that aren't in their native language, is that they lose control of their own work, which can lead to some situations such as copyright infringement without them even knowing, and what they especially fear, censorship. More than a few times, an H-game from a foreign country (usually Japan) gets attention in the west, and it backfires in all kinds of ways back to the country of origin. You might think it's silly, but it's a real fear for them.
Another possible matter, though this is the one I'm not sure on, if you post the link to the download directly, there are a lot of adware type scripts out there that automatically look for such links and can put a lot of train on his bandwidth, which is never a good thing. This is why you almost never see complete links on Japanese image boards and such, instead you get things like:
ttp://www (missing the h) or hxxp://www
All this aside, I don't think this forum in particular is to blame or anything, rather, I think there's a forum or group out there that got a little too carefree with this.
