Fossils occur in Earth rocks because there is life on Earth. Thus far, we do not have evidence of life on any of the places where meteorites come from, so if a rock contains fossils, then it is an Earth rock. If we ever find a meteorite that contain fossil life forms, that would be a big deal, but the burden of proof would be very heavy.
A weak connection between meteorites and fossils (Antarctica used to be a warm place).