What other meanings do you think are implied? riverkid suggested "UN in favor of Taiwan", and you seem to agree with that. (but "in favor of Taiwan" doing what?)
Do you mean that the government of Taiwan has told the U. N. that Taiwan is interested in becoming a regular member again, and that the U.N. has said that it would support Taiwan in this regard? If so, I haven't heard that.
Also, if that has happened, a much clearer headline would be something like U. N. supports Taiwan's desire to rejoin (the U. N.)
In addition, your initial post doesn't say that the "slogan" is official government policy. (is it?)
This is just to clarify the reasoning behind my responses.
Last edited by 2006; 18-Oct-2007 at 04:16. Reason: correct spelling error
To me, it works as a slogan for Taiwan, where everyone knows the situation, but I think it might be much less clear elsewhere, where many people have a shaky knowledge of the situation.