it is big news but what im saying is thw 4th shinbi war the joint forces the 5 kage summit is alot bigger news tha naruto defeating pain plus nagato's name was not known even pains name was not knwon much by the people all they knew was that there was an organisation and there was a leaderwell the news about pain a rinnengan user and leader dying would have been big news, it would be like killing saddam hussein when in a war, of course if the leader of the enemy died whoever did it would be worshipped, like shodaime killing madara was legendary.
the speed doesnt really matter, seeing as sasuke became notorious so quickly after the things he did. naruto even dodged raikage and stronger than bee, and the konoha viillagers know about him so technically the world should.
plus when the kages got back to the village what happened...
they told everyone about the news that happened then made them prepare for war now im pretty sure they wouldnt be worrying about some guy defeated some other dude in a fight coz thts bassically all they to them is some guy
and but they new they were powerful but all of a sudden there kage says were going to war to fight some immortal guy that has lived since the beggining of the ver 1st kages now that to me is bigger news and i would be more focused and more worried about that than naruto not to mention madara has 7 bijuu with him