Seelie territory is enemy territory. [ Maglor points out ]

You are hardly forbidden, but although there are Seelie who are welcoming, there are plenty also who would just as soon kill you for your shard, simply because you are from the opposing side - indeed twas the Seelie Champion who was the first of recent times to do so. I would not venture into such places without due care, although I can do nothing to stop you.