I think the pilot waaaay over-reacted on this one. From Center for Infectious Disease Research & Policy:

"A doctor traveling on the plane determined that the girl had no fever and did not pose a threat to other passengers, the news report said."

If airlines are going to start screening for germs, they're going to be booting a large number of pax every winter - I can't count how many times I've sat near someone who coughed and sneezed for the whole flight.

Also, I doubt CO would have tried this on an adult - would any member of FT would have tolerated being kicked off the flight for a cough? But a teen traveling with a school group was an easy target.