That seems to have been a complete fluke. Here's the patch that was added in m4: https://source.jboss.org/changelog/JBossTools?cs=35266
If you look at the patch (you don't have to), you can see every server except AS6 had the proper facet added....... oops? Seems I just skipped over as6 by accident. I'll make a jira and fix this.