Trivia: Most of the film was changed from its original form. Scenes of Raymond Burr were added exclusively for the U.S. release, and the plot was altered.
Trivia: On isolated Odo Island: On the 1st visit, during the ritual ceremony, Burr stands behind an old villager wearing a black robe with Japanese writing down the lapels, but only the top is visible. Later, on the 2nd trip, where they look down on Godzilla's footprints on the beach, Burr stands near the same villager in the same robe, and the entire lapels can be read: In Japanese katakana script it says "Lucille Anderson", down each lapel. Some Californian's souvenir from Tokyo, perhaps? (00:29:10)
Answer: I don't remember if that line was in the KOTM American cut as well, but in the Japanese Gojira cut, Serizawa, as he is talking about why the capabilities of microoxygen and the Oxygen Destroyer horrify him, mentions that he fears that "perhaps one day he might have to create the Oxygen Destroyer again," and that horrified him. The reason he allowed himself to die didn't have anything to do with stopping Godzilla; it was to ensure that no-one, including himself, would be able to create the Oxygen Destroyer ever again. That was his entire arc in the movie. He has previous scenes in the movie where he explains why his discovery of microoxygen and its destructive capabilities horrified him, and before he went to unleash the Oxygen Destroyer for its first and final time, he had ensured to destroy all the research in his lab that could be used to recreate the Oxygen Destroyer. Finally, he allowed himself to die so that he would erase the possibility of himself recreating that weapon as well.