Why? They didn't qualify by any stretch of the imagination. They finished (effectively) 15th in the overall scheme and since only the top 10 qualified they were nowhere near.
Promotion was the order of the day at the beginning of the season. the Cougars won the league. London and Paris were a) lower placed than the Cougars did not even exist, Featherstone and Widnes were kicked out from the top tier. All these things were travesties of justice and fair play. Keighley did indeed qualify for promotion until the rules were changed half way through the season.