As of July 1st, desk clerk are not allowed to use laptops during their shift. Mind you my shift is from 4am to 8am and I usually put my laptop away at 6am when guests begin to wake up. I explained to my employer that I am not on the internet but i am working on a paid freelance job. I stressed to him that this is affecting my work that would get me to my career objective.
One morning he came down early to get coffee and made me shut the laptop down and wrote me up the next morning. The next day, a fellow co-worker was using a laptop (he relies on it for his outside job as well) and I warned him not to let the manager catch him. he told me the manager already was down, saw him using the laptop and he did not say anything or write him up. Also both managers surf online while on shift.
You don't ask a question here, but I think you are saying, this is unfair. Sure, it's unfair. Unfair doesn't mean illegal. What you describe violates no principle of law that I know about. Employers do unfair things all the time, but that doesn't make them unlawful. My suggestion is that you stop using your laptop at your desk clerk job. Insubordination occurs when an employee violates a supervisor's order. Insubordination is good cause for termination in every jurisdiction that I know of.
I'm not licensed in California so don't take what I wrote above as legal advice. If you need legal advice, please consult a lawyer who holds California licensure. That's not me.