I had Kidney cancer so I have some personal insight to share:
1. He (and I) was lucky they found it. Kidney cancer is typically only found in older patients. The median age of patients is in the 60-70s.
2. The 5 and 10 year survival numbers look ugly because those numbers are for any cause of death and most patients have other underlying health issues that skew the survival rates.
3. If he is having a partial nephrectomy (like me) he will be fine to play BB with out issue.
If if whole kidney has to be removed I am not certain of the impact on his career. I had a friend that donated his kidney to a family member and they told him no contact or extreme sports. My friend did Brazilian JJ and he had to stop and he couldn't mountain bike with me.