I don't mean to throw a wrench in there, but Rhalgr's sign was present during the sealing spell. In fact, each of the giant blue spikes that attempted to hold Bahamut had their respective symbols on the top of them, and if I can pause it right again, you can see a Meteor, Rhalgr's symbol, at the top of one of the spikes.

His power was indeed present, and I think Bahamut was just too powerful.