Adobe is only 'strictly' illegal, because the author said that it was only available to Koreans...
Although this wasn't really enforced. As the download was available on the net. But the website was in Korean, and so out of about 20 files, no one knew which one to download. Someone who could read Korean, downloaded this and uploaded it to torrent servers. Also, but don't quote me on this, it was (apparently) uploaded to AVSIM, but quickly removed as it was challenging Payware companies, and they used this 'copyright' of it not being available to anyone other than Koreans to enforce it. Avsim buried any threads on it, and pretended it didn't exsist.... ::)
So, in conclusion... No, strictly speaking it isn't an 'illegal' addon. But you would be infringing on a copyright (that in all fairness I'm not sure exsists...? Rather that the Author demanded it was only available to Koreans.)
It's a great addon, and I would reccomend it to anyone looking for the most realistic AI pack out there. I had UT before, and it puts these payware companies to shame....

Alex