All 12 nodes free, lvi, pni + colon.

My dad was having stool on and off since last 6 months  after doing colonoscopy we noticed a mass in rectosigmoid region 10cm from anal bulge pet ct said luminal narrwing in rectosigmoid region causing dilation of proximal larhe bowel  he underwent colostomy surgery and is now recovering. doctors prescribed  chemo qfter it was mss and eF of heart 45 percent with oxilaplatin and s1. my question is that isnt oxilaplatin too toxic for high risk stage 2 because in mosiac trail they say that oxilaplatin almost adds neglible benefits in overall life for  high risk stage 2 patients compared to stage 3 patients...also he is very fine walking eating smiling and energetic well i m very confused that after chemo it might not be the same...pls help also is ctdna test or any other tests required to check further or chemo is important. we are giving him superb high antioxidant diet in his recovery days after surgery