got return of true. how would i do the kaska fight again? i dont have any saves from before the fight
Save editing to "undo" the Stellar Tether.
There are fights other than Kaska that can inflict Disarm on Steele: Shade if she uses Disarming Shot, Lorelei if you fail a Reflexes check before combat begins, and the Rat's Raiders as one of their options if they grapple you. The thing is, of all of those, only Shade's Disarming Shot and one of Kaska's disarming attacks use the wrapper that checks for Disarm Immunity; everything else (including Kaska's other disarming attack) applied Disarmed directly without checking for immunity.
In effect, the Smuggler's Quick Draw perk is more useful than Disarm Immune since it allows you to dispel Disarmed for free simply by removing the turn-ending effect of equipping another weapon from your inventory (you can just re-equip the original weapon immediately).