In XMR there exist a flaw involving the keyrings that under the right conditions will allow an attacker to steal your wallets and hijack your addresses. To fix this, anonymity will need to be sacrificed.
The bullshit part is in bold (well it's all bullshit). There may be an exploit in XMR that may work under some theoretical circumstances, but unless Ronald Rivest and Adi Shamir (the R & S from RSA cryptography) screwed up in a way that has not been detected by everyone in the field of cryptography, there is no need to sacrifice anonymity for "keyrings" (i.e. the ring signature system).
And the part about hijacking addresses is laughable too. Signatures and derivative keys in these systems come from cryptographic one way functions. The implementation of these functions are easy to test using known inputs and reference implementations. So, to reverse engineer a signature or derivative key is impossible with current technology except in cases of weak keys.
BCX probably killed coins, but judging from his assertions, any success is more likely related to the mining power at his disposal than with any specific insight into cryptography.