are you talking about the surgery to reverse the colostomy?
if you are, the surgeon is correct and the oncologist is wrong. your friend should wait until the cancer has been cured to reverse the colostomy.
there are many many reasons for this. here are a few:
1. scar tissue is very very vascular (lots of blood vessels) when it first forms. cutting through a field of scar tissue 4 weeks after radiation will be nothing but a pool of blood. the surgeon will not be able to see anything clearly. you will lose a lot of blood. he will not be able to do a good job. 6 months later the blood vessels are gone and the scar tissue is no problem anymore.
2. radiation may or may not get rid of the new tumors. if they do disappear after the radiation, they may grow back. it would be best to keep the colon as far away from the area of cancer so that the cancer would have less chance of spreading to the colon. after the radiation, the tumors should shrink. if 6 months go by and they do not recur, maybe you are cured, and getting reversing the colostomy can proceed.
it is a pretty good rule that decisions about surgery should be left to surgeons, and decisions about chemotherapy should be left to oncologists, and decisions about radiotherapy should be left to radiation oncologists.
disclaimer: I haven't met you. You haven't met me. I haven't the benefit of your history or physical findings or labwork or imaging studies to guide me in making a decision. basing your life exclusively on anything someone tells you over a message board is really not a good idea. the best advice would be for you to discuss what you read on the internet/message boards with both your doctors and see what they think and make your decision with them. perhaps ask them if there is a way you can have a conference with you and both of them at the same time. in person would be best. another option would be for you to get a second opinion from another doctor or doctor(s) who are not affiliated with the first set. you might consider flying to texas or new york for the best opinion you could get - md anderson in texas or sloan-kettering in new york would really be in your best interests given the two new tumors. they are the top two cancer centers in the world.