They can say what they intended to mean, and while that won't become a part of the license, a court may consider that. Especially if this would get widespread as "not tested but meant as a canon interpretation" common knowledge.
To put it in other words, clarifying won't hurt, even if it could have no real effect.
But, yeah, the real way to fix is AGPLv4. And FSF surely can do this.
Sure, they could change the wording, but unless there's a court verdict to establish precedent, there will always be ambiguity.