Twelfth house is considered in Vedic astrology to be the door to next birth. Malefics for the lagna , Saturn, rahu and Ketu when placed in this house prevent the soul to enter this door and cause liberation or moksha.
It is not restricted to rahu and ketu to give moksha to soul but Saturn and Malefics for the lagna could also give liberation to the soul.
I hope there would be many to argue with this.