Commercial banks answer to the government, to the central bank, to their shareholders, and to their non-governmental regulators (payment networks, insurers, etc). This has created plenty of examples of "debanking" of businesses and individuals who bring with them excessive risk due to their history of attracting controversy and/or legal trouble.

Whereas, the government can of course confiscate assets already, including through commercial banks, but generally cannot refuse service. If a CBDC becomes the norm, an account held at the central bank becomes a right, and thus refusal of service becomes a punitive measure subject to statutory and constitutional limits and scrutiny. This is arguably better than the commercial bank situation, where "business risk" is (generally) a valid reason to refuse to provide service.