Scum forgetting the kill is extremely unlikely. Injury or (another) block makes no sense without a claim.
Either BL stopped Newyn, or...hmm.
An explanation that flies in the face of Occam's Razor would be: The scum have a tracker, and BL was watched. They then waited, and decided not to have a kill, to obfuscate the next day. BL's block inarguably implicates Newyn, and with his death the lynch or lose is adjusted by offsetting the balance of town and scum kills.
It's definitely something I would do potentially, but it's a bit unconventional to give up your kill.