(1) The Haki that made GB shook was Shanks' own not his crew.
(2) How are you justifying Shanks intimidating GB from OUTSIDE the Waterfall in the Wano Sea lmao? Shanks wasnt even near the island and yet he intimidated GB.
Im sorry bro, that scene is almost a perfect 1:1 of Aokiji threatening Doffy.
1. Shanks has coc master of all characters what we see and his coc cause his some crew mates to fell down on greenbull . Literally easy way sent attention as shock to make enemy to pay attention you .
2 . Because shanks came to talk to greenbull as voice of all things before to fight or not. As say” hey don’t anything or we will fight you “. If you don’t think it is voice of all things , then how shanks and greenbull able to talk from far way as they can communicate each other perfectly fine . Yaamto didn’t know shanks is talking or know shanks is here depsite he is famous pirate .
It is different than Kuzan on doflimingo because doflimingo didn’t claim he will fight Kuzan next time. And doflimingo wonder who is really Kuzan after for his real goal .
It is same thing as shanks pick fight against Blackbeard at marineford and blackbeard say he won’t fight shanks and his crew today but later time which greenbull say same thing. Shanks talk first , then will fight later after in case it didn’t work.