Makes me love goatbeard even more he lived what he preached.
This also explains why goatbeard was surprisingly chill towards Teach in Marineford.
Newgate knew Teach was only betraying Whitebeard's family, to avenge his own father.
If Newgate is healty/not dying, no way Marineford happens the way it does.
Once Teach knew Thatch had found the Yami Fruit, and knew his father, Newgate, was near death... Teach's mind was decided.
TBF from Teach's perspective, too, he's got to live for like 30 years on the best Pirate Crew in the World.
Teach probably figures he already lived a good life under Whitebeard, and decided to sacrifice his own happiness to destroy the WG he despise beyond all