I'm afraid that sometimes the tomato warning gets slightly misunderstood. Given that you have a properly seasoned CI skillet or Dutch oven, cooking with tomatos is just fine. It's storing something with tomatoes in it that should be avoided. So when you are done cooking, and everything has cooled down just transfer the leftovers to something else.... rinse your Dutch oven, dry it in the oven and lightly oil.
Now if your seasoning is still in the immature stages .... obviously it would not have the same defenses as a well seasoned skillet or Dutch oven, and this is where you see some of the warnings. For the same reason, you would not use a griddle with an immature seasoning to make pancakes either.