Presumably, the extension binaries plug into the FOSS Apache licensed product using some kind of API and therefore might better be shipped and sold separately. This, for instance works with proprietary httpd Apache Webserver modules (shared objects linked against webserver headers). In that case there would be no reason to use the commercial bundled version as the core would be essentially identical to the FOSS version that's included in (almost) any Linux distro.
If such separation is not possible, the commercial version spells trouble. For one license wise, but on a technical level it's probably a fork. A fork might have its own security flaws and bugs, but will also need to maintain updates and backports from upstream / main branch. The commercial entity is responsible for this, whether they intend to or not.
In theory, this could lead to a better commercial product, but in practice I would recommend sticking with the FOSS version.
