Aperture Exporter is now compatible with MacOS 10.14 Mojave. You can get the newest version (1.4.0) here right now and is available for purchase directly from us. We are unsure of when we will return to the Mac App Store.
Our other Aperture products, however, remain incompatible with Mojave. As a result, we've removed them from the Mac App store. They still remains available for purchase directly from us. Please keep in mind that we are not currently supporting any Mojave users for those products.