I think playing both sides is fine, as long as metagaming isn't involved. 

[@Lemons] Yeah, 50G is absurd. He could go even more, but because the strength of the gravity is reciprocal to the amount of time he could use it, so if he goes any further, he might not be able to maintain it for not even a second. And I only intend to use 30-50G in extreme conditions, so I have to make consequences to prevent him from abusing the power. Otherwise he would crush everything and everyone in his path