In the update. It appears that while the NBP2.0 are equipped shotgun kills will activate Disintegration.

Omfg they just took that part out. I read it when weekly update first dropped and was like holy shit thst is dope and gonna be a wrecking machine: Shotgun kills trigger disintegrate +perk chosen in melee column WHILE COOLDOWN IS OFF? Along with extended duration of disintegrate in general. I got a massive stiffy. Went back an reread it again anf they took it out....went soft instantly. Unless they don't want to reveal that just yet. It's a pretty big improvement and I know why, they need to make old sub classes as relevant as the new ones.

I think it meant after cooldown. You had to have it available, basically using the shotgun as your melee instead of your melee. It would be an answer to the T-Rex arm issue Titans have.