Here is how I equate this. I have cable. I run my cable next door to my neighbor so he can watch it. Is it legal? No. It provides a broadcast to someone who isn't in the market and paying for it. It is rebroadcasting it to another location.
One to one, you could probably get away with it. One to many and you are illegally providing a service that DirecTV provides with the Ticket.
There are other legal uses for this as well. If you have Sunday Ticket and are travelling, you can watch the game from your broadcast legally from a remote location. If you want to watch the signal from your main TV on your PC in your room, etc.
This could be used incorrectly and illegally, just as a DVD burner could be used illegally. It doesnt stop Best Buy from selling them.