I know it sounds strange, but hear me out.
Harry Mudd was last seen trapped on a planet of super advanced androids that operated with a shared consciousness. These androids wanted to study humans in order to serve, and were willing to imprison the entire crew of the Enterprise to achieve that goal. They were not malicious, merely single minded.
As we know, the crew of the Enterprise were able to escape via a cunning use of silliness, which the androids could not process. But when the Enterprise left, Harry Mudd was still on that planet. Up until this point the androids had tried peaceful methods of obtaining humans to study (adopting attractive non-threatening appearances and serving humans) which were unsuccessful, as we saw in the episode "I, Mudd" (S2E8 of TOS).
Here's where my theory comes into play. The androids still had the directive to study and understand humans, but they had reached the limit of what they could learn from mere observation. One of the Alice series gyndroids said that their medical facilities were capable of placing a human brain in an android body, so they are capable of incorporating biological material into their technology, and if they incorporated Harry Mudd into their shared consciousness, they could learn a great deal more. But the Norman android clearly stated that Harry Mudd was a flawed specimen, and their need to understand humans would likely remain after assimilating him. They would likely seek out new specimens to learn from, and they would likely abandon their peaceful approach since it was not as effective as merely assimilating the specimen into their "collective".
I know that the Borg's directive is purely to assimilate all organic life, but this could be a natural conclusion to Norman's claim that the best way to serve humans is to control them. What better way to control humans than incorporating them into a single-minded collective?
Bear in mind that if the chronology of this theory does not fit, the Star Trek universe has had multiple instances of time-travel, and it is possible for any chronological inconsistencies to be explained away with time-travel.
Having outline my little theory, I have a request. If there are any things in the Trek Universe (excluding the rebooted cinematic universe) that could support or invalidate my theory, please alert me to their existence.
Is there anything to support or reject this hypothesis?