The other attorney is correct. However, most applications ask whether you have been convicted. Once expunged, you can say no. It is questionable how many employers actually run background checks for most positions. But if you get finger-printed as part of the application process, it will be discovered. Good luck.
Employers can do all of that. What the judge did is grant a request for dismissal under PC 1203.4; that does not seal or erase your record which now will show your arrest, your conviction and the dismissal of the conviction.
An "expunged" conviction is legally dismissed. However, that does not mean that the case history is sealed or destroyed. Case record information is public record. Record sealing under Penal Code Section 851.8 is different from an expungement. However, by regulation, a private employer cannot ask a job applicant about any offense dismissed under Penal Code 1203.4. (Cal.Code Regs 7287.4(d).