"Some of them? ...Sakura, how many are there?"

That's not the important question, and he knows it. Chouji shakes his head. He hesitates but knows he'll have to ask eventually. "Who?" Basic intelligence gathering training as well as knowledge gleaned from another conversation here prompt him to immediately countermand his own question. "Wait, don't tell me who unless they already know. Other people can hear this if they try, right?"

Chouji doesn't want anyone to find out about their own death through an overheard conversation. He won't be responsible for that.