“I presume that at least means that although they may decline to serve you or allow you entry, you at least can’t be arrested.”
I believe you’re correct. I think a lot of the crazy videos of people getting into physical confrontations over masks is because they won’t leave. If you don’t leave the minute management tells you to you’re automatically trespassing and in the wrong.
A private business can most certainly have you arrested for trespassing if they ask you to leave and you do not.