Not killable, seki-able!
I promise you, in a series of unfortunate events I would certainly be killed in that situation.
The first response to consider to “why X, not Y?” is “X”. And it’s the answer here.
Ah. Oh. Oops.
(Bit of necro i admit)
R18 without any reading. Why? Because this kind of cut in this shape is a verywell known tesuji to capture the 2 stones. I hope you memorize that shape as an offensive weapon or reverse be aware of it when being on the bad side.