Well, how closely do they watch him? Won't they notice if he's gone for hours at a stretch each day? (For that matter, won't the Malfoy boy notice? Surely HE'S not Even if he can conceal his absences from the adults, his friends are another matter.)

I don't want us to take unnecessary risks, either. But given how much the Junior Auxiliary already knows, I'm not convinced that excluding him from the secret of 12GP is going to keep anyone any safer. He may need a safe house as badly as any of them.