I'm reminded of "my phone has 64g of memory". It makes sense to a lay person, that memory would mean storage.

This is inevitable. We either invent new words, or we use existing words from the natural language. The latter will always lead to confusion at some point, because the domain-specific concept doesn't exist in the rest of the world. To represent such a concept, a word would need to deviate from its everyday usage.

I think Rust's "unsafe" is an okay choice; the "vouching" is a feature about memory safety after all.