VSTHRD103 mis-fires in synchronous local methods declared within an async member method #1003

Task Foo()
{
    return Task.CompletedTask;

    void CompletionHandler(CancellationTokenRegistration registration)
    {
#pragma warning disable VSTHRD103 // Use DisposeAsync instead.
        registration.Dispose();
#pragma warning restore VSTHRD103 // Use DisposeAsync instead.
    }
}