Lolz. You Dunning-Kruger think the issue is about least path computation, but the quote clearly states it is about determining the algorithm to decide who has the accurate database of the topology and dealing with conflicts/faults in the accounting thus the need to revert to only the stable nodes along with RP routing:
No. I asked a question, I did not create the asumption. You were the one who said that the sources can be found on the WWW so I've stumbled upon the article with those algorithms. You can't blame anyone else besides your own logic.The RP model shifts the burden of finding sources of multicast content from each router (the (S,G) notation) to the network (the (*,G) notation knows only the RP). Exactly how the RP finds the unicast IP address of the source varies, but there must be some method to determine the proper source for multicast content for a particular group."
Interesting, but that still does not confirm that the implicit meaning of his statement is that is it not possible (rather than just being difficult).Get off my lawn Lauda. Stop trolling my thread with your ignorance, else I will report you to yourself (the mod). 
I didn't know that properly replying to a thread was equal to trolling. In any case, I would not be the one handling that report. I might as well repeat this part:As soon as you resort to ad hominem, the "I'm an expert" story and your credibility goes down the drain.