FinCEN wouldn't be the agency to say non-MSBs are exempt from KYC. There may be a kind of FINRA member firm that is both regulated by the SEC and not an MSB, b

FinCEN wouldn't be the agency to say non-MSBs are exempt from KYC. There may be a kind of FINRA member firm that is both regulated by the SEC and not an MSB, but many kinds, such as broker-dealers are regulated by both FINRA and the SEC and subject to the source you linked. Yes, OFAC is a different discussion with different considerations.