He wasn't wrong. He wasn't right either but, he wasn't wrong. In a large group they are an easy target while alone it would take them too long to finish so their best bet is to do what Gali and Lewa did pair up and help each other collect the masks. That way they remain small enough targets he can't find them easily but, are still able to finish collecting much faster than normal.
"So my hand is cast. Now, I must pierce that which the Toa hold dear. Anger amongst them will threaten their precious unity. Hunger will consume their duty. And Fear will keep them from their destiny. They will not disturb you."