Unfortunately SEN is not profitable because it isn't paying for the cost of the infrastructure. I've heard £120m quoted as the total cost of acquiring and redeveloping SEN. Even if the £700,000 EBITDAR result miraculously turned into a retained earning figures it would still take Stobarts 171 years to recoup their investment.
Prestwick is much the same in that it will have on-going capital expenditure requirements that are not met out of the current revenue streams. Hence the need for a sale.