Its hard to perfectly recreate every nuance of a map i'd imagine. For instance, in every different version of slab the window played a little differently and in 2fortron the button reacts totally differently to the point that it changed the map totally. The top route has made D marine practically useless on 2forts in 2fortron which is just another reason why its considerably less popular than 2fort2k1.
getting it right is more trouble than its worth honestly. He could redo the maps, but thats wasted labor. This is nearly instant gratification and it gets the job done.
He could strap on a set, but why do all the pumping when you can just jump in, shoot your load and everyone is happy.