Can you skip the train segment in Lufthansa's Airail system?

Hello dear Gutefrage community, In January I am flying from Cologne to Miami via Frankfurt. The Cologne-Frankfurt leg will be served by ICE. The transfer time in Frankfurt is less than an hour. The train arrives in Frankfurt at 8:50 (without delay) and departure is scheduled for 10:00. Boarding will probably begin before 9:30. In…