I feel like this would dilute the drop rates of other items like Ascendant Shards. What about adding it to Master Lost Sectors as a potential drop? Would make Master LS more appealing too. Just a thought.
Nightmare Containment is the easiest source for Ascendant Alloys. At one point, I was almost full in all three postmasters from just mindlessly running them. Unless you lack the season pass for Haunted, it is the best source for farming them.