Loki is facing Imu and Oda has yet to show his hybrid while Luffy is recovering. The way things are going, there will at least be another chapter between Loki and Imu before Luffy coming to help and it might be at that point that Loki's hybrid will be shown with them ending up tagteaming against Imu
And judging by Luffy's statement(needing to be at 100%), most likely his Nika form will be even more powerful than before
And unlike Luffy, Loki doesn't have a 5 minutes timer, so he is essentially playing the major role here especially since we know Imu is also on a timer(can't fight in the lower realm for long)
And this is a weakened Loki to boot