There are a few issues.
if there is 1 kill tomorrow after megastack it does not necessarily mean the megastack target was town, either the scum could have randomly targeted the weak doctor, or the weak doctor was already dead.
If there are no kills it does not mean the target is scum. I do not see a rule where scum is forced to kill each night so they could simply choose not to, more or less forcing a mislynch.
The only diagnostically definitive result is 2 night kills, if everyone plays along and there are 2 night kills then the megastack target MUST be scum as the weak doctor.
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Lets analyze n4 after megastacking
we enter the night with 3 players, if town dies without killing scum then town loses. town can prolong the game by
1. jailing the scum > requires 1 of 2 remaining town players to be jailer
2. healing the scum kill > requires cpr ordinary or jailer to target correctly
town can win outright by
Killing the scum player in the night > requires cpr or quack
Not sure what the best strategy for town targeting is on n4.