Learning Shunkan Ido is the only thing that makes much sense (even though it makes no sense compared to just swallowing his pride and having Galu teach him it), as it'd make little sense for there to be some other technique Goku wasn't able to learn in a year that Vegeta will have to master in a few days at most. Current Vegeta being far stronger than that Goku shouldn't make a difference when Vegeta stated Yardrats are naturally weak and it was established the Ginyus were conquering the planet prior.
Vegeta did say that they have many strange techniques, so perhaps there is one he had heard of that Goku declined learning in favour of Shunkan Ido due to being less of a necessity against a scenario different from Moro. Nevertheless, it would seem difficult to buy that unless it's pure magic immunity and even then, there should be no reason the battle prodigy Goku couldn't have learnt it within a few days.