EA has evolved his practice over many years. He has used both triangles and circles in the past so he understands their significance and their use, which is something I think many people forget. They just hear him say he doesn’t use circles or triangles, and as beginners, they’re like, “Oh, okay,” and then they wonder why they don’t get the same results or things go badly.
A circle will not prevent a spirit from “running amok.” However, a binding triangle will.
If you are not following a tried and true system of evocation, then you will have to take your chances with possible parasites and impostors. Most systems of evocation make that impossible, but if sounds like you aren’t using any system in particular.