Flying through a sea of cosmic creation energy is quite easy—is not the kind of statement Arthur would make, even as a joke.
Right now, Arthur had set aside his usual playfulness entirely and was in full serious mode, because if he wasn't careful, the high density of creation energy in this region could very well kill him.
As he flew across the great distance at a constant speed, he began to notice the gravity around him was gradually decreasing.
At first, he assumed it was another effect of the Seed Engine's presence, but when he activated his Anti-Divine Gravity Authority in preparation for a further decrease, he quickly realized that the decreases in gravity weren't coming from the Seed Engine at all.
They were coming from the planet itself.
It wasn't just reducing the gravitational pull on him, it was trying to invert it all together, forcing him off its surface.