I'm also a little concerned he may push MUA if my ROM doesn't improve much before then, but honestly, I will probably decline it. Would I be wrong in refusing that if he mentions it at 7 weeks?
You would be completely right to tell him no, or even

no! You are seeing improvements in ROM so it's not adhesions preventing your ROM so an MUA would only put you back to day one of recovery. I agree that you are doing too much and the swelling that results from too much activity is limiting your ROM. In this recovery you need to really listen to your knee, if what you did during the day causes additional pain or swelling that night or the next day you have done more than your knee was ready for. Less is often more in this recovery. It sounds like your surgeon only gave you the "miraculous" knee recoveries, playing golf at 6 weeks. This is a 12-18 month recovery and you can't do much to speed it up, but pushing too hard can certainly slow your recovery. You might be able to play golf now, but I guarantee you'll pay a big price for it.