Age has nothing to do with it. As SirW said it comes down to what a person wants for themselves. For many people it is not about sex but control. If sex is an important part of what you want and need from a BDSM relationship, then that is what you must look for as a prime characteristic in a dom.
In the real world dreams do sometimes come true but they must be tempered by reality. Holding a dom to that high an ideal may be letting yourself in for a letdown if things are not perfect. You may overlook a perfectly suitable candidate because of the dream ideal.
Also, a relationship needs to be customized and built. It does not start out perfect.

Barton