M'kay, after reviewing the clip several times, it looks like there are a couple factors coming into play at the same time. One: it looks like the tether came into contact at the tail end of the timer. Sometimes this causes a target to seem unaffected even though they appear to become tethered. Two: Tethers will suppress supers, but they will not stop the animations used for the supers if the super was in the process of being cast. This means that if, say, a titan started a smash, became tethered, then somehow untethered himself before he hits the ground (fell out of range, tether ended, etc...), he could theoretically still execute the smash as normal. Roaming supers will be automatically canceled. And Three, I couldn't help but notice at the time you died, you were red bar. This could mean any number of abnormalities, but in this case I suspect it means that the tether on his screen could have been gone before the tether on your screen was, or somehow cause an additional delay. As for the tethor suppression timer, I think the change was intended to immediately suppress someone hit directly. Anyone with a decent damage resistance (i.e. Stormcallers with active supers) the arrow will fail to kill them on a direct hit, because the damage resistance is still in play. However they have significantly less time to counter you with their super before they lose before the suppression activates and nullifies their super.

Nightstalker is completely useless now. Smoke grenades now have a delay on invis, pve enemies don't flinch and walk right out of shadowshot, and guardians jump right out of both smoke and shadowshot.