The death of Alexander in 1249 happened to coincide with the death of Galfred de Liberatione, Bishop of Dunkeld, in the same year. So instead of falling from a high-profile job into obscurity, Richard was elected to the diocese of Dunkeld sometime in the year 1250.
The death of Alexander in 1249 and Galfred de Liberatione, Bishop of Dunkeld, in the same year led to Richard's election as bishop of Dunkeld in 1250.  This happened instead of him falling from a high-profile position into obscurity.