My philosophy is always stand up for yourself (and others) so that you make it better for others who may not be able to. I’m sorry you had this experience, but I’m glad you didn’t get injured, because you could have been had you not stuck to your guns. Others may not be so lucky, so if you are able to, I hope you take the opportunity to explain to the gym owner how their employee was dangerously pushing things she should not have. I hope your next experience is with someone who does a better job.