Maybe so. But that person was an inspector at an IAEI section meeting who said it in front of a bunch of CA inspectors and contractors in an open discussion where anyone could have challenged him. I’m not from the west coast though so never took the time to research it.
Looking back, you said 'roofers', not 'roofing contractors'.
There's a potentially big difference there. This thread is about contractors, not employees.
In California any employee of a solar contractor (or electrical contractor, or GC when applicable) can install solar panels and DC wiring, that is true. So such an employee's previous work experience could be as a 'roofer' (and they make really good solar installers when it comes to installing rooftop mounts). But that's informal. There are no certification requirements for the employees of solar contractors or GCs. (There are for electrical contractors, and if you ask me if I think the discrepancy is messed up: yes, I do, and the solution should be to relax the requirements for electrical contractors. But I digress.)
However, neither a roofing contractor or any of their employees can do the same, (unless the roofing contractor also holds one of the other license classifications). So that's going to exclude most 'roofers'.
As far as the latter, the laws and regulations are very clear and cannot possibly be construed any other way.
Where it might get interesting is a BIPV solar system, i.e. where the solar and roofing are one and the same. But even so, it's a huge stretch that a roofing contractor is qualified to contract for that. Maybe to remove it, or integrate non electrical parts of the roofing to it, but not to install the electrical. Arguably anyone contracting to work on BIPV needs to be licensed as both a roofing contractor and a solar (or electrical) contractor, or if they are a GC they can do it since it involves two trades. (Now when it comes GCs installing solar and any other electrical, even if they're not-very-otherwise-qualified... yes, in California they can do that legally, as long as the contract involves two trades other than framing.)