I also miss a discussion of how the protocol avoid denials of service once it's assumed that the UDP comes from any address -- if every packet from any address actually has to be decrypted.
2 We do not prevent against a denial-of-service attack where an ac-
tive attacker intercepts packets and resends them under its own IP ad-
dress to fool the server’s roaming detection. Such an attack would not
compromise the confidentiality of the connection but would disrupt it.