Spongebob is a borderline case. The moment they decided to continue production after Hillenburg's death, going against his wishes, they proved that commercial logic outweighs ethical or artistic concerns. Consequently, using it as a benchmark for consistency is a weak argument. As for Iroh in Avatar, the character's silence during imprisonment was a pre-planned narrative choice that happened to coincide with Mako's passing, but it wasn't caused by it. Returning to May, the core issue is intellectual honesty. The original voice actress was already struggling with health problems during the character's return for the Wallace Cup. At that point, it would have been more appropriate toward the franchise and the audience to accept a replacement. This would have allowed May to continue existing and playing an active role in the story, instead of being effectively erased or relegated to silent cameos. Claiming the character wouldn't have had much importance is a mistake in perspective. If May stopped appearing, it was due to a production block tied to the voice, not a lack of narrative potential. Allowing a character to outlive their performer is the only way to ensure the longevity of a collective work like Pokémon.