User blog comment:Daddy Danjer/Why need the Keepers if there is the catalyst??/@comment-64.229.84.185-20120509020605

It could be due to the fact that the catalyst does not interfere at all with the cycle, rather he/she/it lets the reapers and the keepers handle it. This could explain why the catalyst didnt restore the signal, didnt close the mass realays once the reapers started attacking and did not stop the use of the crucible.