To me this is the most likely reason. Twitch didn’t need a Nerf. Unless the Defenders were brain dead, there’s no way Twitch is getting more than a handful of deployables between both her gadgets. Not to mention that she’s countered by a well placed mute jammer.
Not only did she not need a Nerf but no one was asking for one. People at high levels only target batteries and Miras because they know their drone will got shot pretty quickly, or if those gadgets aren’t in play, use them as normal drones due to how quiet they are. People at low levels waste the shots by tasing people, but they think that is helping, so at the end of the day, everyone is satisfied.
It seems to me that the Devs plan to introduce a new op that fills a role that crossover with Twitch’s. For a lot of people, the first set of ops decides whether or not they get the season pass so they want the 2 new Ops to be amazing and desirable. The best way to do this, if indeed the new Ops role crossover with Twitchs, is to vastly reduce the effectiveness of the competition.