It looks like the usual BBC anti-Brexit opportunism, taking facts out of context.
If you follow the link on the BBC web page, the references to Netscape appearing on Page 921 are in a section entitled “ANNEX LAW-1: EXCHANGES OF DNA, FINGERPRINTS AND VEHICLE REGISTRATION DATA”
s/MIME functionality is built into the vast majority of modern e-mail software packages including Outlook, Mozilla Mail as well as Netscape Communicator 4.x and inter-operates among all major e- mail software packages.
So, it was just a ‘for example’, even if somebody writing it today would choose a different example.
It looks to me as if that entire Annex is pretty much a copy&paste of existing (not old) EU legislation, applying between member states. Sure it would be good to get it updated, but if it means rehashing their own internal laws, just for the benefit of the Brexit agreement, I suspect the EU would be reluctant to do so.
It may or may not be a concern that EU law, applying to member states, mandates insecure protocols for DNA data exchange. Does it? If so, that would be a reason for optimism that we will be making our own laws, in future. But I’d not expect BBC news to report it like that.