A semicolon may be used to join two closely related independent clauses. The rule here is that both the group of words that comes before the semicolon and the group of words that comes after it should form complete sentences sharing a close, logical connection. In other words, you can check the use of semicolon by writing the two sentences separately, ending with a full stop. If each of them independently is a fully complete sentence, then the use of the semicolon is correct.
In the cited sentence, what comes after the semicolon doesn't make clear sense as a standalone sentence, starting with "According to which…", so the use of the semicolon in the full sentence, to me, seems utterly unjustified which I can't say about the use of a comma instead of it.
By the way, the link you provided doesn't lead to the cited sentence.