My mistake, the video I was referring to was from BadEmpenada. I am very wary of him as a person and his material, but this video is excellently researched and gives a good socialist lens on the horrific nature of the Shining Path and their leader. His description also gives a very long and thorough reading list centered on leftist and South American sources that you might want to look into.
Also The PCP's violence was aimed at the people. That's what makes them reprehensible. They commit heinous acts of terrorism against the poor in Peru, are associated with Nacrotrafficking and cartels to make money, they utilize child soldiers as young as 10 to fill their militant ranks, and so on. They are not using "a means to an end", they are just using a mean that is so vile and reprehensible that every leader and associated member deserves death or imprisonment at the very least.
They accomplished nothing leftist related, and instead murdered trade unionists, feminist activists, Marxist professors, and foreign emissaries. They probably pushed back the leftist movement in Peru by decades if not centuries with their actions.