PCS evaluates the program regardless of technical mistakes; i.e., a program with falls may have high PCS.
This happening is wrong too. As mentioned above, a program that is clean/error-free should be rewarded with better presentation marks. Unfortunately with "popular" skaters they could still score higher in presentation with falls and errors, while a newer skater could go clean and their PCS may be kept at bay.
I'm not saying Shaidorov is quite a 9-level skater yet, but take the 4CC SP for example where he was clean (and still decent skating) and got 7.25-7.75 on PCS (7.71 overall), while a skater like Miura who is more established errored on his opening quad and also had a fall (errors on 2/3 jumping passes), and same with Tomono erring on 2/3 passes, and they scored 8.07 and 8.21, with PCS as high as 8.25 and even 8.75.
GOE/PCS is also hella subjective in itself too, and clean skating still isn't reward on either if you're not an established fave. For example, in the same SP, Matthew Newnham had a lovely triple axel in the SP with difficult entry transitions, nice air position, pretty effortless, and flow/extension on the landing, but the GOE it obtained was in the +1's mainly because nobody had ever heard of him (way underscored in his spins/steps too). He had beautiful lines and choreo and highlights, but because he's a relative nobody to the judges he wasn't rewarded - even for a 'clean program' - I mean, a 5.75 from one judge for presentation?!?
A clean program shouldn't receive any points bonus. It will encourage skaters to dilute their content, and it's so subjective as to what makes a program 'clean'. Their reward for skating cleanly is obtaining higher GOE points for clean elements. If a skater falls in the middle of their program randomly (e.g. Petrokina in her Euros FS), they give up -1 with the fall deduction, whatever the 'clean program bonus' is, and likely (hopefully) a reduced presentation score (since logically speaking, the overall impact/impression/presentation is compromised). That can be quite a swing.