It should never have been acceptable under any Alert condition for a crewman to end up dead in an abortable operation, and Kirk should've been in hot water as soon as Finney was presumed dead.”
My understanding is that the ion pod doesn’t have any communications equipment. The CO communicates with the officer getting ready to enter the pod with an estimate of when he’ll have to jettison it. “I don’t think I’ll have to jettison for the next five minutes or so.” Or “Make it quick, this storm is looking bad.” The CO is responsible for estimating how long preparing the pod will take, waiting at least that long, and sounding a red alert prior to jettison. The person in the pod can hear the klaxons, but doesn’t have any other communication with the rest of the ship. He’s hurrying through a manual procedure, so he can’t use a communicator easily. Starfleet failed to provide any kind of handsfree communication.
This is a poor system that would probably have been improved by TNG and would probably not be allowed in a civilian job. But in a TOS-era Starfleet job, this risky operator-judgment-intensive procedure was seen as acceptable.