My very unhelpful and very subjective opinion is just to avoid the problem by never buying tinned tuna, but that's because I think it tastes completely disgusting and I wouldn't ever want to put it in my mouth.
If someone actually does like it somehow though then maybe you could just use the oil for cooking in, make a salad dressing, brush it on to some bread and grill it, or something like that. I think it's normally sunflower oil so it's pretty versatile, just in this case it has the massive disadvantage of tasting like tuna.