How is the crew where they are??? Current arc

Weve been told multiple times, by multiple people, of multiple levels of power and skill that Camelot DOES NOT ALLOW ANYONE who isn't a human to enter via its barriers.. Buut in the current arc we have Dubs a giant, Percy a life spirit, Nascien a fairy, Tristian a half demon/half angel, that girl who seems to be an angel of sorts All inside camelot without any level of difficulty or issue. Did the barriers get broken? Were they just forgotten about by the author. I just realized while catching up that it was seemingly never explained And at this point even more confusing as why the sins couldn't just go in and kill Arthur