Someone with expert flyer access csn look up the MCT for us, but 25 minutes is a very common MCT across all airlines for non-hub connections at airports with consolidated operations. (DL at AUS is an example).

As far as the seats go, haven't you ever seen seats with X's but not shown as occupied when you try to select a seat after purchase? I think you got awful service here, and you are right to complain? But I very much doubt the agent was intentionally keeping you from the seat you wanted.