Okay I see. Nah it was the right play because there was no way I was gonna self-doctor at that point. You would be stupid to NK me with only the two of us left in the POE. And I had no idea what a bus driver was so I wouldn't have anticipated that play.
I very much doubted that you would self-doctor, but I might as well have taken into account the possibility, however small, given that I believe the night action would have worked the same otherwise.
Why is it bad for a doctor to waive NP1? I know people scumread it but why. What i looked up seemed to indicate doctors should play conservatively.
More fundamentally than the answers other people gave, because waiving actions denies you information. There is an old saying in firefighting: "Never pass up fire with the nozzle". Since the hose has a fixed maximum flow rate, you should, as much as possible, have the hose running at maximum capacity and pointed at the fire, even if you are not aiming it optimally.
Not to sound like I am the leading authority on how to play this game, but information in Mafia is paramount and in limited supply, and abilities give you information. Therefore, you should always use your ability unless there is an overwhelming reason not to, even if there is a risk of harming town, especially considering that the information you gain may outweigh the harm you might do. It took me a few games to overcome my hesitancy to take the risk of hurting town. In a game of imperfect information, you have to take risks.
The 2x restriction on your Doctor might have been a good enough reason to override the default of always using it, since you had little information to guess who was worth protecting, and, even if you never got any scumreads, your probability of stopping the night-kill would become higher as players died.