Actually prop surfing isn't against the rules at all. What is against the rules is glitching to get to areas that are otherwise inaccessible. So sure, if you want to prop surf right off the edge and kill yourself that's fine, but if you go to that "secret spot" you are violating server rules. So the argument that you should be able to prop surf to get to an area you cant normally reach is literally "I want to do something that is specifically against server rules". Prop surf if you like... but if you go ANYWHERE that you cant get to otherwise you are fair game for being slayed/kicked.
TL;DR YOU ARENT GETTING PERMISSION TO GO THERE