Worksheets are the behind the scenes support for the form ... when they are ready the state is ready.  That form is a mail in only form ... it cannot be efiled ... you are reading the chart correctly ... 

https://ttlc.intuit.com/community/forms/help/state-forms-availability-table-for-turbotax-individual-...

Does it mean returns could be filed later without worksheets OR everybody with self employment income can't e-file at all?

Link tells "Schedule C: Business Income" and that it's unsupported. No mention on any worksheets and if you mean TurboTax worksheets they are never filed.

So the question is should everybody with self employment income in CA now file on paper? As this link tells "unsupported", no date when it's going to be available. Last year it was possible to e-file.

First only forms, schedules and statements are ever sent to the IRS or state ... they are never sent worksheets. 

As to why which forms are not supported for efile that is a question for CA to answer ... they are the ones who decide which forms can be efiled. 

From the CA site itself ... the Sch C is not on the list of forms that can be efiled ... I suspect it has to do with the craziness that happened earlier in the year about classifying employees vs subcontractors ...

https://www.ftb.ca.gov/tax-pros/efile/individual-efile-forms.html

In May 2019, the California Office of Tax Appeals ruled very recently that income from California-based clients is taxable as California source income.

For some discussion:

https://www.coblentzlaw.com/california-office-of-tax-appeals-gives-precedential-authority-to-bindley...

https://money.stackexchange.com/questions/95243/is-self-employed-work-performed-out-of-state-for-a-c...