I'm surprised your therapist and doctor don't agree on this, but I totally agree with your therapist on this issue and with you. your surgeon probably doesn't want you to develop a need for the cane, but walking with a limp only causes other parts of your body to compensate, potentially causing more problems. Your therapist is right on this issue. Walk with a cane to help you not limp when you're out and about, but when you're at home (and go see your doctor) try really working on walking w/o the cane AND the limp. you do need to strengthen your muscles and until you do you will have a limp, but no need to stress your poor healing muslces.
use it for a little while, but don't rely on it to get your around.