You can't necessarily take one application of a general ability and use it to assume a character can do another similar. I could technically use that same logic to say that Galaxia outright resists Hakai since she resisted her own soul hax. But that would be dump, because she resisted having her soul stolen; not being destroyed. Beerus can resist existence destruction, which includes soul erasure, but he has not shown the ability to resist soul theft. This hax is also based on magic and not ki. You're right. My bad. It's a little complicated. In the manga, star seeds are not souls. They are more like an informational seed for your being. Souls exist separately along with the physical body and both cease to exist when it is removed / stolen. (tldr; Its really, really meta) Beerus actually should resist the destruction effect in the manga. I don't think that's being debated. But for the anime, its just simply soul theft. The body still exists but turns into a soulless monster...