Jin Yong was never historical accurate.
Zhu Yuanzhang (White Lotus sect) became Ming sect and Quanzhen priest Qiu Chuji who died same year as Genghis Khan in 1227 was in The Return of the Condor Heroes story in 1267, 40 years later.
Of course he took liberties with the details. After all, he writes sword fighting novels. You can't compare him to historical novelists like Gao Yang. But "never" is an overstatement.
It is true that Qiu Chuji was invited to visit Genghis Khan. If you bother to read the footnotes in She Diao, Jin Yong explained the liberties he took with the Qiu Chuji character in his book and noted the difference between the character and the actual historical figure. Few writers of fiction would go to such length to inform and educate their readers.
The Ming Cult was based on both Manichaeism and the White Lotus Sect. Jin Yong explained this in the endnotes of Yi Tian too.