These could be backed by the same SEC and FINRA requirements kind of have to see how the regulation plays out. I'm not super optimistic about it given their current attitudes towards crypto but this does more directly mix with the normal stock market so who knows where the rules will come down on this, they can regulate anyone claiming to offer tokenized securities to hold them purely 1-1 on the stock transfer agent of the companies for example, you don't have to regulate the 'blockchain' as an amorphous concept there will individuals/companies offering these tokens after all.

> I can go to FINRA and the SEC if someone does not deliver or properly custodian my security. Who do I go to when the blockchain doesn't?

You can go to FINRA and the SEC.