You are doing business in the state.
CA has never made an issue of unlicensed preparers or preparers unlicensed in CA preparing returns. They recognize all EAs, CPAs and Attorneys from other states to practice in CA.
That being said, if you are organized as an LLC, Corp, Partnership or any entity organized under the SOS of your state, they do want you to register as a foreign entity and pay the fees and taxes associated with doing business in CA. They do like their nexus.
Not a problem for me as I am a SP, so my Sch C just goes to them with my 540NR, no special filing required. I keep my workpapers for my allocation of income and expense but they have not audited me on my application of the market based sourcing rules. The statute is running on my first year filing an NR with them, so I might see a letter at some point before it runs out.
Tom
Longview, TX