WARNING: The following contains spoilers for Boruto: Naruto Next Generations Episode 176, "Blockade the A-Un Gate," now streaming on Crunchyroll.
For most of Naruto, Orochimaru was a villain, and even in Boruto, there's reason to be suspicious of him. As much as he redeemed himself by helping against Kaguya in the last war, he can't be forgiven for turning his back on Konoha as a legendary Sannin and working on sadistic experiments. He's tried numerous invasions, played nation against nation, killed leaders like Hiruzen Sarutobi and worked for the Akatsuki.
Naruto kept him under close watch as Hokage, although we're now discovering Orochimaru has means of sneaking out, as seen in the Land of Valleys. What's interesting is, while it was thought he'd helped Konohamaru and Team 7 out against Kara's Deepa and Victor, the snake ninja might actually be poisoning the investigation of the terrorist cell.
When Naruto's council meets to discuss the God Tree drama and Kara's agents, it's clear they've had spies in their own village. The network runs deep and to make it worse, they don't have much intel from Victor's lab as data was either destroyed or hidden. All they know is there's a vessel out there, obviously the manga's Kawaki. However, while Konohamaru points out the staff didn't know much as the lab was a forbidden zone, one person who knew a lot was the unnamed Secretary.
The problem is, when the red-haired woman went to kill Mugino and the lord of that land he was trying to escort back to Konoha, Orochimaru jumped in and dusted her Thanos-style. It seems he was being heroic and saving them, but as he told Konohamaru later, he didn't care for his allies -- he was just there to recover his work on the Hashirama Cell. This means he could have been covering up things he didn't want Naruto to find out, which is why he killed her and tried to murder Victor.
It's the perfect way of keeping the guise up, covering what scientific research Orochimaru was doing on the First Hokage. If he was genuine, he'd let Naruto's scientists in, right? So he's definitely hiding something and these Kara workers had to go. Other theorists believe Orochimaru stymied the investigation by not killing the Secretary, but by kidnapping her.
The dusting is a new jutsu never seen before, so many think it was a means of abduction to decipher what she knows. Also, he can learn what Victor's lab discovered on the Hashirama Cell, and with new secrets to mine too on their own research, this could be Orochimaru's way of upgrading his work leaving Konoha thinking he actually tried to help out and clean up his mistakes of old. It's the kind of sinister move he's known for. Seeing as Naruto can't really monitor all he does, it sets Orochimaru up perfectly for another heel turn in the near future.
