He is actively looking for ways to antagonize California. This issue and homelessness, he couldn't give two craps about. He is just looking for ways to make California look bad or powerless, and he's just starting a fight because he's going to use that fight on his red-state roadshow. California will never give him its electoral votes and therefore it's of no use to him. BUT, Trump is astute, and knows that people across the country don't give two hoots about California either, and will be happy to trash talk them.
Many people live their lives or conduct their work by seeking out friends and allies. Trump actively seeks out enemies. And, it works (if you concede that ascending to the most powerful leadership role in the world is a success), so is he a dummy or a genius?