It seems that the moment that Death Monarch had enter Pandemonium, Loki had ordered that all gates were to be open and all protection formation of the Centre Palace to be lifted up since the report came that Death Monarch is coming to Pandemonium.
He had even summons Shinji but he was a little late and Death Monarch had ripped off the formation before Shinji even had the chance to open it.
In any normal circumstances the lifting off a protection formation is an unwise move unless one wanted to surrender.
That is because when one lifts the protection formation that protected their territory others could take the opportunity to attack,
But when Loki issued that order none of the high ranking members of Pandemonium even utters any word of objection.
It is not because they fear Loki that much or they respected him that much. That is because they were confident.