If IPSec is a complicated, commitee-designed and NSA interfered technology, and moreover not recommended by information security researchers, isn't a detail such as support for post-quantum algorithms irrelevant?
We are of two minds about IPsec. On the one hand, IPsec is far better than any IP security protocol that has come before: Microsoft PPTP, L2TP, etc.
On the other hand, we do not believe that it will ever result in a secure operational system.
It is far too complex, and the complexity has lead to a large number of ambiguities, contradictions, inefficiencies, and weaknesses.
It has been very hard work to perform any kind of security analysis; we do not feel that we fully understand the system, let alone have fully analyzed it.
https://wiki.strongswan.org/projects/strongswan/wiki/IKEv2Ci...