It doesn't work when there's no network connection, wonder if it would be possible to filter out and automatically block notarization traffic, or if it's all encrypted with cert pinning to prevent this type of MITM+filter.
Dropping packets when there is an otherwise working connection could potentially make the delay even worse depending on timeout or retry strategy used by Apple code. I assume that in the fast case without network connection it checks the network status flag and doesn't try to do any network connection at all.