Depends whether or not Mew's Psychic abilities would be capable of affecting Ginyu, since if treating Piccolo's Moon Bust as an outlier, they ought to have comparable speed. That is, assuming Ginyu gives it the chance to do so. If Mew's Psychic capabilities have the typical limits of DB's laws, as with Chaozu or Kaioshin, they'll just be worthless, leading to Ginyu zero-diffing the Pokemon.