To put it simply: It’s almost never within bounds to directly side with Nanotrasen unprompted.
You may act like you’re siding with them, just as they may act like they’re siding with you, but there should always be an attempt to keep the narrative within parameters and some form of betrayal planned later.
Had you sent that message to the captain and then sold out random people who weren’t traitors as if they were, that’d be a fine gimmick to keep the narrative going and interesting, especially if such “traitors” were your assassination targets. The station would have to think twice about wanting to revive them to some extent.
If you’re already arrested and bargaining for your life, this is a good time and place to try bargaining, but again keep betrayal in mind.
This was done near to the start of the round before any shit hit the fan and went on for the duration of the round. There was no intention of deception because they were cursing and salting at the captain up and down in dead chat after being executed.