I've never read anywhere about the abductor allowing Eliz taking anything out of the bathroom...I remember reading that MK saw them entering the bathroom, but nothing was said about removing anything from there.
Pure speculation, but there are a few things that support this thought. I already mentioned the family's feeling that she is alive in my earlier post. So lets speculate as to why the perp took her into the bathroom. Did she need to relieve herself? Did she need a lighted room to put on her shoes? Did he want a place to give her instructions before they left the house? Did she need to grab some kind of medication?
Ed refuses to answer when asked directly if anything was stolen on the night of the abduction. If some medication she were taking was missing then you wouldn't identify that as stolen. If it were a serious kind of medicine that Liz needed for her general health then I think we would have known that by now but who knows in this case. So many mysteries. Anyway, it's just something to kick around.