As jwfacts says, it's hard to disguise what you're looking at on an iPad - unless you are sat in the corner of the KH with your back to the wall. Even then, you would probably get a few raised eyebrows for sitting there glued to your iPad.
Kingdom Halls are an environment where everyone shamelessly looks at what everyone else is doing. Brothers doing the microphones will peer at people's Watchtowers to see how much underlining there is. People peak over shoulders of others and constantly glance around to see what others are doing. Let's face it - there's so much boredom in that building, you can't blame people for having wandering eyes. In that kind of atmosphere, it's difficult to imagine someone successfully spending any amount of time on any kind of website other than JW.org.
Cedars