Yes; that's bad advice. It looks like in your picture the failure is where the keel stub meets the hull (concave section on the exterior). This section distributes the keel loads out to the hull and it is important that the glass fibers are continuous through that section or you could have a failure (the crack could open or the keel and keel stub could fall away).
I'm really not sure how you would fix this such that it would be a reliable/safe repair. Personally I think it is one of those problems where the cost of fixing it might exceed the value of the boat. You need a second opinion on it; and I think you might want to look into a claim against the surveyor for not finding such an obvious problem before purchase (accredited surveyors have insurance for these situations via their Association IIRC).
Putting epoxy in the crack is not a suitable fix. My speculation is that the boat was severely grounded pushing the keel up and causing cracks to the bilge side of the keel stub; or dropped off of a lift causing the same.