Not sure I totally understand what you're asking, but the 360 has a metal mesh grill over the opening. The throat of the SEOS has nothing.
I'm talking about this piece here Looking at my driver it seems like its some type of fabric. I'm worried about little fingers and objects, I won't be using a grill. You think its possible to add a metal screen without affecting the output? Perhaps a piece of window screen sandwiched between the Waveguide and CD... If that won't work then I could add a piece of speaker grill cloth for another layer of protection.
That screen is adequate for protection if it is similar to the DE250 screen (I haven't had a DNA driver in my possession).
I also noticed its not a straight shot to the diaphragm. There is some kind of plastic piece in front of it, not sure what that is.
Yes, the phase plug will keep you from seeing the diaphragm in many CD's. You would have to push pretty hard to poke a hole through that mesh, I don't think you'll need to worry about it.
That screen is a bug screen. Its meant to keep bugs out of the CD for outside PA use. In Geddes' speakers where a foam plug was to be used thus rendering the bug-screen redundant, he recommended cutting out the bug screen so the transition from the interior of the throat of the CD into the waveguide could be filled in/smoothed with clay. Basically if you were to mount the CD to the waveguide without the screen you could feel a tiny little gap between the waveguide and the end of the throat profile. You fill this in with putty (like modeling clay). This is that last little detail.