You are really reaching here.
UHURA: Message from Starbase Eleven, sir. Received images from Talos Four. In view of historic importance of Captain Pike in space exploration, General Order Seven prohibiting contact Talos Four is suspended this occasion. No action contemplated against Spock. Proceed as you think best. Signed, Mendez, J.I., Commodore, Starbase Eleven.
Obviously the trial was more real than that. Spock still PLED guilty. Mendez still saw the events unfurl. It’s just that Spock was not found guilty because of a suspension in the rules FOR VISITING TALOS IV. He still committed mutiny.
Many officers have committed mutiny, that was never in question. But Burnham was definitely charged with it, found guilty, put on legit trial, and put in jail because of it. So her mutiny is criminal record.
Spock's supposed mutiny never even went to trial and he never got a criminal record. Don't forget they needed 3 Command Officers to have a court martial trial, and Mendez was never there. It was just the Keeper's illusion.
Spock's situation is nowhere near the severity of Burnham's recorded mutiny, that basically the entire quadrant knows about.
I can understand why Chekov wouldn't know since he is just a little kid at this point in time.