Ales, your lib scanning code works like a charm :-)
The only piece that was missing is to uncomment the injection of libArchiveProvider into ClasspathFactory:
<bean name="WeldClasspathFactory" class="org.jboss.weld.integration.deployer.env.bda.ClasspathFactory">
<constructor factoryMethod="getInstance" />
<property name="system"><inject bean="ClassLoaderSystem"/></property>
<!-- property name=libArchivesProvider><inject bean="LibsDiscoveryService"/></property -->
</bean>
The fix is committed to JBoss AS trunk.