Alright I have seen the video about 3 times and as I understand the situation.
First of, what you did is KOSable. Not only did you prop abuse but you also pushed a player in a hazzard zone
Secondly he slayed you for the reason that you used the minecart to push the detective in (Prop pushing, abusing the usage of a prop) and that was correct. You did prop abuse and therefore he slayed you. But there is one thing that Froyo did wrong that he shouldn't have.
I am going to talk to him about that thing and it is:
He should've slayed you as soon as he saw you push the guy with the minecart into the hazzard zone instead of taking advantage of the situation and try to kill you himself first.
I will basically tell him that if he witnesses a KOSable rule break that he should use his staff powers instead of killing the rule breaker with his gun.
Also the rule that you broke is:
1.7a Prop Abuse
No abusing props (grabbing them with the magneto stick to shield yourself, push players away, kill players, to climb or fly with them etc.) [The poltergeist traitor weapon or other prop manipulating weapons void the no prop killing/pushing rule]
This can be locked.