As per https://forum-en.gw2archive.eu/forum/game/crafting/How-do-I-get-traveler-runes-off-karma-armour/
The concept of Karma items not being salvageable is difficult when you want to retrieve upgrades off of them.
Why not give Karma items (kegs, jugs, drops, drips etc) instead of materials along with the upgrades so that we can get our expensive runes and sigils back. As long as the amount of Karma returned is less than the karma cost of the item, this prevents karma items from being a trap with respect to upgrades. This is especially true for lvl 80 exotics which are likely to be considered “end-game equipment” for an extended period of time (until they are finally replaced with time-gated ascended), and as such going to get expensive or high end upgrades.