This CBC chaining thing is my all-time absolute favorite cryptography conspiracy theory, because on the IETF list where it happened (it happened for IPSEC, not for TLS, for what it's worth) Phil Rogaway pled with long-time standards body people --- even took up a petition of cryptographers, including Rivest --- and was openly and viciously mocked for the attempt.
The US government had no need to corrupt IPSEC standardization. The IETF did the work for them without prompting.
Hello, the US government paid the IPSEC devs to include weak and backdoored algos back then. All revealed during the Snowden era