You tagged this question with "food-safety" and used the word "safe" in the title. It seems that you are confused about what food safety is.
Food safety means "the chance of you being delivered tomorrow in the hospital with food poisoning is astronomically small". Just that. It doesn't cover anything about taste, suspected long-term health effects, and so on. It is not about whether you feel safe when you eat it, it is whether it meets the standards set by a regulation agency.
Degraded fats are irrelevant to food safety. There are people who don't like eating them (and some who don't like the idea of eating them, while eating them every day - they just don't realize that their favorite recipes take the oil above the smoke point) so there is much advice around to avoid heating fats too much. It can have different reasons, such as taste, fear of carcinogens potentially occuring during oil pyrolysis, and so on. But this is not food safety advice.
So, the most direct answer is: it is safe because fat heated to any temperature is safe. (At least pure fat - if you heat whole fish to too low temperatures, it is not safe).
Beside answering the safety question, I want to point out another misconception. When you have a chemical mixture, the matters get complicated. Its melting (or burning, etc.) point is not necessarily melting point of the easiest-to-melt component. I cannot tell you if the fat in the fish undergoes degradation at baking temperatures or not, but just because it would have undergone it if you had had pure fat, this doesn't imply that this also happens when it is incorporated in fish cytoplasm or in a cake batter.