That's pretty much my interpretation, too, but it does appear to present a contradiction.

It's not a contradiction, the license of use is personal. You are only allowed to play your own games, and your friend can only play his own, sharing an account is not allowed. Although of course GOG has no way to check if an account user is actually its owner.

Unless, well, he goes posting on their own forum about it, but who in the world would do that!

As people stated already GOG is one of rare companies that actually cares about it's users.

In other words: Nemoj 'leba ti. Cak i mi ovde mozemo da platimo ponesto, pogotovo kad je jeftino. :)