I think he's basically saying that any changes to the ground game need to be particularly well thought out. Because subs end a fight and takedowns themselves score heavily, any changes to those mechanics would have a huge impact on the game. I think he's just saying he's afraid that the proposed changes could make the ground game overpowered.
Personally, I kind of agree with Grasman here. Granted, I've always preferred stand up fighters, but I do have a few wrestlers with solid gnp, and I haven't had a problem executing it in their fights. If anything, my wrestling has gotten more effective in my more recent fights.