What case does the antagonizing speaker make about the possibility of accepting Ender into the academy

From the text:

"I've watched through his eyes, I've listened through his ears, and tell you he's the one. Or at least as close as we're going to get."

"That's what you said about the brother."

"The brother tested out impossible. For other reasons. Nothing to do with his ability."

"Same with the sister. And there are doubts about him. He's too malleable. Too willing to submerge himself in someone else's will."