Maybe he wants to lead a elite group of ninjas, those who are loyal and active the most. this will lead to no gnw packs being lost cause of casual player or any other reason.

More people in the group means it can be leveled up faster, besides that it isn't necessary to have big numbers as you only need 27 to fill Saturday's battlefields.

I prefer to have a lot of people in my group and give everyone a chance, so I wouldn't. But it's up to you :>