I don't believe any of these would prevent a massacre attempt in 2024.
The Sea Wall route will still have no CCTV.
In 2024 he would know he would have to ring his AM. Or answer his own call. No one knows what his stance was in 1985.
His DNA would be inside WHF. But he was always there.
The police throwing away carpets early would not make much difference. The blood in the hallway was Nevill's. The blood by June was hers.