I don't know. It could be the tie-in is just being handled by another writer, or it could be that Slott is done. If Slott's doing 700, then this could eat up one of the issues until then to help him fill up the remaining issues.
The big thing is that it's a Sue issue and NOT by Slott. KInd of telling by Marvel. Yippie-ki-yay, Marvel Universe is brilliant though.