In my opinion, once a track athlete is processed and signs the Statement of Conditions to be on the USA Track and Field Olympic Team, they are Olympians as long as they hold up their end of the agreement.
Sign and then you get injured and don't compete - still an Olympian.
Sign and spend the entire time in the relay pool and never see the track - still an Olympian.
Sign and then get busted for drugs and kicked off the team - Olympian status revoked.
I admit, this is a little strange for the marathoners because they aren't processed until the track trials.