Absolutely!
In fact, I'm going to pick up a tomato and try it out for breakfast tomorrow. Sounds yummy.
ETA: Reading the recipe, I'm thinking I might want to sprinkle a little salt over the whole thing after it's assembled (or maybe just on the peanut butter). We get unsalted, unsweetened nothing-but-peanuts peanut butter, and the author of the recipe is rhapsodizing about the taste combo of salty peanut butter and tomatoes. Our peanut butter isn't salty.