Is your feature request related to a use case or problem? Please explain

See: quantumlib/qsim#893

Describe the solution you would prefer

Implement a flag to allow/disallow state vector copy

How urgent is this for you? Is it blocking important work?

P3 – I'm not really blocked by it; it's an idea I'm proposing based on principle

Describe alternatives/workarounds you've considered

Provide additional information or context (e.g., screenshots)