Possible Clues:

• Not nuts, but just for the present
• Everybody at that place is mentally competent
• Quite aware there are no absentees
• Quite normal for the present, perhaps
• No-one absent, nor absent-minded
• Nobody in this place is compos mentis
• Not wanting everyone to be present
• Nothing here is completely sane?
• Got enough sense for the present
• One might have the whole of them for a present, perhaps (3, 5)