Retaliation as a witness in an unemployment appeal hearing

A close friend of mine was recently denied CA unemployment benefits due to conflicting reasons for termination by her former employer. At the time of discharge, she was told that the reason was for negativity. The employer then turned around and told the EDD that she was discharged because of "actions which annoyed co-workers". At no time during her termination meeting was the subject of actions annoying co-workers ever mentioned. She has formerly requested in writing an appeal hearing. She has spoken to a former co-worker who agrees that the reason for her termination has nothing to do with annoying co-workers and that the alleged negativity was widepsread in the Department of the Company due to poor management decisions over a period of time. She has asked this co-worker to serve as a witness should an appeal hearing be granted. The co-worker does not wish to serve as a witness out of fear of retaliation by the employer, namely that he will be terminated himself for this action. Under CA labor law, can the employer legally terminate an employee who serves as a witness against said employer in an unemployment appeal hearing?