Would you have preferred he did the full RCT, billed you for the full fee,
then extracted the tooth ?  Sometimes. we do part of the RCT, to see if the
tooth will heal enough to be worth-while doing the whole thing (including
crown and build-up.)  Sometimes, the doctor who does the RCT, is not the
doctor who will be restoring the tooth, so the RCT doctor will do enough of
the RCT to start some healing and get the patient out of pain, then have the
restoring doctor evaluate the tooth to see if it worth saving.  You get to
pay for half the RCT because half was done.  If you have your car in for
body work, and the shop puts new front fenders on both sides, does some work
to the metal to make them fit better (but so that they cannot be returned or
used on another car), then you decide to scrap the car instead, does the
shop get paid for the work they did so far ?  Do you have so little respect
for the doctor that you think his time is worthless ?