Concurrency, sure, I can see thinking of that as a separate thing (as some people from Google have advocated for). But aliasing isn't a memory safety violation, it's a cause of memory safety violations (and other kinds of bugs besides). The first example from the linked post is straightforwardly a dangling pointer dereference, and I don't understand how the people behind safety profiles can claim that it's out of scope just because it involves aliasing. Did they say something like "this assumes your code follows these non-machine-checkable aliasing rules, if it doesn't then all bets are off"?
Sure, I said “aliasing” to mean “these rules do not prevent memory unsafety due to misusing aliased pointers.”
I hesitate to answer your question, but my impression is the answer is that they’re just not shooting for 100% safety, and so it’s acceptable to miss this kind of case.