User blog comment:Water Dragon Slayer Shawn/Theory on why Gajeel and Natsu couldn't pass Freed's barrier./@comment-99.250.223.69-20140627211952/@comment-7418318-20140627213512

If that had been the case, Laxus wouldn't have been surprised about Natsu being locked in. And also it would have shown up along with the other two rules. As far as we know, you can't hide any rules when putting down Jutsu Shiki.