Jester suspend stops Jester not just from talking, but from interacting with the jet at all.
This is required in situations where the player wants to do RIO activities in single player. This is because Jester will manipulate sensor and system controls autonomously while the player is in the front seat, even when he's not been asked to do anything.
The result is the player fighting with Jester over switch settings while they are in the front seat, even momentarily. This is particularly noticeable during startup, and is incredibly unhelpful given that Iceman has no capability to start the jet, and the player must perform both roles, even if they only actually interested in the back seat cold start.
Until this update, there was no AIRIO equivalent for Jester Suspend, so the only way to access the command was to disable AIRIO and use the wheel.