The tornado full of spatial shrapnel was coming closer and closer to Felix. While Marshallo watched from the sidelines, he was an honorable fellow. So even though he could take this situation, to try and mess with Felix and his tornado attack could land, he didn't do anything of the sort.
Felix would have his hands full, trying to stop the tornado, and while Marshallo was certainly weakened and out of energy, any actions from him would make Felix have to split his attention.
Splitting his attention in this situation would put him in a perilous situation. If the tornado swallowed him and he died. That wouldn't stop the tornado from destroying the planet.
The tornado's strength was currently increasing at the highest speed.
While it was also absorbing the broken spatial shards that it was continuously creating by itself.
