I suspect that the system might argue that since your mate is single he has no food cost during the week and would have pay under save as you starve. As for his accommodation charges I seem to remember that there was a clause which allowed singles to escape the charge if they had their house up for sale. Of course the problem comes when they get an offer and dont actually want to sell.
Surprisingly, although it is illegal to discriminate against someone on the grounds of marital status it is not illegal to treat married people more favourably.