The misunderstanding of your objection comes from the fact that I’ve just never heard of it in the context of “giving good weather and taking it away” as in “Indian giver”. The fact that they both have the word Indian the only connection I can make to what you’re saying. The only references I can find to a pejorative origin is in articles from years ago saying that the phrase possibly needs to be changed because of possible negative origins. Obviously culture hasn’t decided it’s necessary to change the phrase (yet). The fact that it’s used as a positive metaphor for non-weather things should be considered too.