It has an option to zero out allocations/deallocations. I wonder if it would be useful to randomize the memory instead. It seems like this would help surface bugs better than either zeroing it or leaving it alone?
Rather than random data, it is more typical to poison with a repeating pattern (like 0xAAAAAAAA). This is usually easy to spot in a backtrace, even with minor mutations.
The point of the allocator is security, not debugging.
Perhaps it would help even from a security perspective, though. It would make it harder to scan the heap for deallocated memory regions, for what that's worth.
As long as results are different on every application run and app crashes when there's a mismatch, you don't need anything as strong as SipHash since your previous guesses don't narrow options for your future attack attempts.