Generally when I see more than one status effect on a move I expect the save on those effects to roll separately. But the silence and stun always without fail expires at the same time when disintegrate is cast.
It replicates without fail regardless of circumstance.
If it was supposed to work this way then great, I’m fine with that but part of the attraction to that troop in spite of the slot machine mechanic of the instakill is disabling both traits and mana gathering. If both effects wear off at once always it makes the troop less effective and rather inconsistently at that.
No video or screencap, just test it out, it happens every time.