I think this is already covered by a different area of law: false or misleading advertising prevention.
If you buy a TPM that won’t codesign your MacBook’s bootloader (or that uses a compromised signing key) and it was advertised as an equivalent replacement to the OEM’s TPM, that advertising was false. This isn’t much different from buying a smaller hard drive for a computer: just because it works in the machine doesn’t mean it’s as big as the old one, and if it was advertised as 1TB and only stores 500GB, then the advertising is false.
If you buy a TPM that won’t codesign your MacBook’s bootloader (or that uses a compromised signing key) and it was advertised as an equivalent replacement to the OEM’s TPM, that advertising was false. This isn’t much different from buying a smaller hard drive for a computer: just because it works in the machine doesn’t mean it’s as big as the old one, and if it was advertised as 1TB and only stores 500GB, then the advertising is false.