I agree the fact she was out all night was irrelevant- l believe the issue was that apparently Claudia said she was with a new boyfriend. Not the casual relationship she was in with a married man, whose identity is known to police. So is this Acomb man?
It seems to me that the police thought Acomb man was the publican they arrested for perverting the course of justice. He was the one who said they had never seen the side of Claudia being portrayed by the NH gang. Maybe it was him. Or was it this Anthony guy. It seems they met there in the weeks leading up to her disappearance. This might explain why she wasn't in the NH that much that week. She was off somewhere else, with someone else.