How often have you used the track and have they ever given you problems when you were using it? You got the tone that they want to close it off, but they haven't, right? If you don't make it an issue and just do your stuff quietly, they probably won't care. Just use the track when they aren't around and don't draw attention to yourself and you should be okay. Seems like you're worried about something you aren't using much.
With one of the best sprint coaches in the country right there, maybe you should think about joining the team.