A Serial Killer is a solo, uninformed third party. They are not burdened by TMI. It is not difficult to be towny as Serial Killer. It is not that difficult to be towny as a wolf, either, but you will get tripped up on pushing agenda or treatment of partners, both things that Serial Killers do not have to worry about.
The issue, of course, lies in the fact that being too towny will cause the wolves to attempt a nightkill on your slot, so I’m not sure Arctic’s play is optimal from a Serial Killer here. But we know that the Serial Killer, whoever they are, likely did get hit by a nightkill, so I don’t think that’s a particularly convincing point against him being Serial Killer.