Here is some information, one respected well balanced source, on when is a stress test needed, and nuclear vs exercise.
Choosing Wisely | Stress tests for chest pain
To the OP, as you have suggested that your being fit should have gone into the decision making process, I would respectfully disagree. You presented with acute chest pain. Your past ability to exercise did not preclude your having a significant cardiac event at the time of this hospitalization. Had they said, "Well, she is Beachbody Coach so we don't have to evaluate her heart, she must be fine." that would have been terrible care.
As to who ordered what test, I can't tell from your posting. You said you were seen by a PA, and then said a doctor ordered your test. A PA is not a doctor and despite your telling the PA you wanted a treadmill, if the MD the previous evening had ordered a nuclear test, that order would still apply. I don't know what your blood work showed or whether there might have been some concerns on your baseline EKG that they may not have even mentioned to you as they can be non-specific.
You can be 100% certain that some technologist in the cardiac lab did not make the decision of what stress test you would receive. They were following an order from someone. And as someone else posted, if you objected to having the test it is completely within your rights to decline it. At worst this will result in someone coming to explain to you the pros and cons and that if you die from an MI on the ride home they told you to have the test (CYA informed consent).