Their Sunday morning services are oriented towards non-believers and maybe they feel that worship is rather meaningless to those who have no relationship to the One being worshipped and hence cannot really participate. I have found this to not be true in the sense that non-believers seeing authentic worship are influenced even though they can't fully participate.
I was there on a Sunday morning, and I should note that we were told that there was "worship" on Saturday night. At the same time, I'm sure a lot of folks only came on Sunday morning. I can understand not wanting to overpower the "seekers" but it is after all a "church."