“There’s good reason to get antibiotics if you have the strep virus. It can turn nasty in ways you really don’t want.”

Strep virus? I assume this is a typo. You mean there is good reason to take antibiotics even if a virus is causing your symptoms? Sure. There are such things as opportunistic infections. They are rare especially if the virus isn’t too severe, but yes they happen. The antibiotics are very unlikely to hurt you so why not? The only tangible harm is more disease resistant bacteria and rapidly escalating medical costs. Neither one of these is a consideration for that doctor treating that condition at that time. It might even be unethical for the doctor to not prescribe prophylactic antibiotics once you have presented yourself to him.