Why was B-4 disassembled?

Question

In the new Star Trek: Picard series, we see a disassembled B-4 kept in storage at the Daystrom Institute in Okinawa.

The last time he was seen on-screen was on Star Trek: Nemesis, when he was depicted as an android with limited capabilities if compared to the more his more "advanced brothers" Data and Lore, but nonetheless it was certainly a life-form, even if one with a limited intelligence.
And the reasoning behind Data's defense and his right to live in The measure of a man could certainly apply also for the less intelligent B-4, in the end.

Why was he disassembled and stored away like an "item" instead of being regarded as a life-form and consequently with his right to live (despite his status) recognized and protected?

He is told to be not like Data at all, but this seems to be a rather feeble reason to deny him the right to live, and doesn't seem like something that some of the more idealistic and humanist characters in the Star Trek universe could easily look-upon, especially Picard himself.

Are there some other reasons of his current state that maybe I have missed?

Answer 1

** WARNING: SPOILERS for Star Trek: Picard Ahead**

The reason given in-universe was ALL positronic-type developments had to cease and any androids/robots, ie Synths, disassembled after the "attack on Mars", by the order of Federation council.

Since it was initially thought to be a programming error in the synths, the Federation Council placed a ban on synthetic lifeforms. Androids such as B-4 were dismantled, and the Daystrom Institute was restricted to "theoretical" studies on synthetics.

-- Memory Alpha

The decision was not well liked, as that also meant Riker/Troi's son cannot be saved due to the ban on positronic devices.

With all active positronic matrixes shut down, people who would contract mendaxic neurosclerosis, such as Thaddeus Troi-Riker, would eventually die from the illness without treatment

-- Memory Alpha