cheating is technically kos as the rule suggest regardless of the scenario it is
Last Request Rules:
LRs can be forced when there are 4 or less Prisoners left alive.
A Guard is not allowed to cheat or delay during an LR unless dealing with a rebelling Prisoner. A prisoner who cheats or delays during their LR is KOS.
Guards cannot interfere with LRs they are not participating in.
Last Requests must be reasonable, cannot be timed, and must be agreed to by a CT. If a prisoner's LR is interrupted they may request another one.
LRs are considered to be complete when the winning party kills the losing party or wins Rock Paper Scissors. A Prisoner may request to do another LR after the previous one is completed, but Guards are not required to honor this request and the Prisoner may be killed.
A Prisoner is allowed to harm/kill the participating Guard if their LR implies that the Guard can be harmed/killed. The Prisoner can be killed if they rebel (I.e. shooting another Guard during S4S).
but you dont have to kill the T even if they are kos. it's pretty shitty to kill a T that accidentally cheat LR or a bug occurred that cause the T to cheat LR. You can literally avoid the whole situation by just allowing the T to LR again, not killing them over technicalities or boosting KD as a guard. The whole point of rules is to make it fun for everyone and enjoy the servers, not making it uptight and strict where only one party enjoys it.
Since JB itself a pretty complex game-mode, making situations like this not kosable can really make things very confusing for guards knowing whether the T's are kos or not. excepetions that create gray areas specifically.