They can definitely sue you to compensate the amount they invested in you like course training and accommodations ( if you used their place to stay and eat). But it is very unlikely that they will do it because these business are too shady. To be honest, your friend can actually sue them for decent amount of money by showing emotional damage as they sent him/her to the client with fake details , getting him fired and keeping him/her into pressure to use fake resume/details and force him/her to work for position that you are not even qualified for.