OP here. Thanks for the links and discussion re: HIPEC. The results don't sound super compelling; I'll share w/my sister and brother-in-law. I'd seen the French study which had sounded more promising.
The vit. C has been very helpful with the chemo side effects, and apparently there is some data to support that it aids in chemo-receptivity, which with a BRAF 600VE diagnosis seems well worth it to them, so he goes weekly.
No Oxiliplatin to my knowledge.
The ND's protocol is based on a lot of nutraceuticals and diet, which is typical. I understand that maintaining strength and weight is critical. Because he hasn't had the extreme nausea, my BIL has been able to maintain a very healthy diet and even gained a pound or two, so it works for him and I think that's an important note. He hadn't even had treatment yet and a medical practitioner said hey, don't change anything/ eat the milkshake, which seemed to set a bit of a low bar. NB: We were on vacation together and he had a margarita. Actually, two. The wheels didn't fall off.
I think what's important is he is doing it as he feels he can, and he feels a degree of empowerment making those choices, and those choices are evidence-based and backed by a provider on his team —and he feels they have made a difference.
Thanks again for the thoughts on the HIPEC from the trenches. It's truly helpful.