[While it makes him seem like a nosy old man by telling him all these things, he means no harm. Knowing your allies is just as important as knowing your enemies.]

The others probably won't be so happy if they find out about this...

[With "this" he means the notes, at which he points.]

... And me helping you with it. Especially because this is sensitive information. But it would be more fatal if this got into the hands of the enemy if we're honest.