Why didn't the Borg drones in "Regeneration" become individuals?

Question

In the 23rd episode of the second season of Star Trek: Enterprise, a couple of Borg drones are allowed to regenerate. Assimilation ensues. Why did they start assimilating things instead of becoming individuals just like every other drone that was disconnected from the Collective before and after the Battle of Sector 001 (First Contact)?

Hugh was liberated before the Battle of Sector 001, and he eventually accepted having become an individual. Picard was liberated before the Battle of Sector 001, and he immediately went back to being an individual. Seven of Nine was liberated after the Battle of Sector 001, and she showed no hints as to having a pre-programmed directive to assimilate things that had to be overwritten before becoming an individual. Seven was also severed from the Collective earlier (presumably before the Battle of Sector 001), along with three other drones when they were stranded and forced to go camping to survive. All of them reverted to individuals before being forcibly rejoined and recovered by the Collective.

My best guess is that something in the wreckage of the sphere was continually broadcasting a directive unique to the circumstance, but I'm looking for something a little more specific than that for an answer. I'm also looking for an in-universe answer, and not "because the script demanded it."

Answer 1

When Borg are disconnected from the collective they will try to establish a local collective with any Borg who are in their local area.

From Memory Alpha Borg Collective:

Subsidiary or ad-hoc collectives between several individual drones could also be established with and without need for a vinculum or other repeater-type device so long as the drones' subspace transceivers were strong enough to reach the other drones or substitute vinculum.

And "assimilation ensues."

The cases of drones turning into individuals you mentioned were special cases: Picard was disconnected when the cube was destroyed. Hugh was separated after his rescue by a subspace dampening field while in the brig (I Borg). Seven's link was destroyed by a power surge while she was distracted by Chakoty (Scorpion, part II).

Answer 2

In each of the three "liberated" cases you mention, the individuals were disconnected deliberately, by Starfleet personnel. The only reason Seven doesn't start assimilating people immediately after her Borg ship is destroyed was because she held to the non-assimilation agreement with Janeway, and because the collective allowed her to act as an individual for easier communication with the ship.

The drones in Regeneration were not severed from the collective. They could still hear each other through the neural link. So they started building their own collective by assimilating the scientists, and kept going until they had enough Borg to modify a ship and start heading home.