Yes if Shiki wants something to go up and Fuji go down the thing will likely crumble I agree with you.
But I don't think the power of Shiki is inferior : if Shiki touchs the ground he has a lot of possibilities that can bother Fuji. Shiki powers if he touches water he can create a lot of things with water etc while Fuji can only be more brutal with his power.
Shiki real weakness is that he has to touch things first. But I think his gravity power are more versatile.
So I don't think Shiki df is weaker
But I don't think the power of Shiki is inferior : if Shiki touchs the ground he has a lot of possibilities that can bother Fuji. Shiki powers if he touches water he can create a lot of things with water etc while Fuji can only be more brutal with his power.
Shiki real weakness is that he has to touch things first. But I think his gravity power are more versatile.
So I don't think Shiki df is weaker