Through the Valley of Shadows - S2-E12
Continuity mistake: As Gant is trying to inject Burnham's eye, in wider shots the syringe is noticeably further away from her eyeball than it is in close-up shots.
Continuity mistake: Michael invites Spock to play chess. She presents a board with three levels. Later, when the game is underway, the board has seven levels by the addition of four smaller boards. (00:17:50 - 00:21:25)
Answer: Perhaps they didn't want to take the risk that Control - a tactical and strategic analysis program - would choose to place its entire core programming into a single fragile human body (Leland), despite previously demonstrating the ability to decentralise, duplicate and transfer itself to numerous computer, cybernetic and organic systems. If any trace of the Control program still existed, it could make another attempt to seize the sphere data.
Sierra1 ★