Unless I missed something, there is nothing else saying now that you can't activate Multiattack with Multiattack. Am I interpreting this correctly? Of course, you could still only do it once and you'd need a large number of available effects to activate to make practical use of the ability to do so, but I think something may have slipped through in the wording here.

Under Free Actions in Section 1:

Glad to know I'm not the only one that had that thought.

Oh, right. I forgot the general rule while I was just scanning for new stuff. That's a relief!