It does if that money's the difference between making a profit and a loss and they can keep pointing at the accounts saying "look, we're still making a loss, we're spending fuck-all, need to be careful and that".
SD hasn't replaced other sponsors. It's extra, new sponsorship, so there should be no impact to the club accounts. And sponsorship of this form doesn't provide tens of millions of pounds. It may provide one or two, which isn't going to make a difference to our P&L, especially when we don't have other costs like interest on debt (which would normally cost a few million).
Their logo's all over the shop man, what do you think was on the advertising boards before Mike Ashley bought the club?