to me this concern says more about you than them. if you feel above it all then be real about that aboveness and go run some super serious race, name brand one, NYRRC, XC/TF as an unattached, go full snob. don't give yourself room with "fitness test." put the pelotas on the block.
be aware at some point your body will start imploding and you will be no better than the locals and are you going to ever merge back into the community or is it about being separate really.
if it's more that you feel like a ringer or awkward, what is the real difference between someone who has talent at the socially accepted youth time vs. gets into it in their 20s? they can win awards but you being NCAA are too good to do it? how is that really different? is it an ego thing? are you scared you lose? in which case you're retired, should never run again, and take up something else.
setting aside ego, if it feels awkward and is really an intermediate test, you can always do the above -- eg, stop short -- or you can finish and if you do win then you refuse the rewards for it, or donate them/give them away.
my two cents one other way of dealing with this is take up new events or distances. then it's less, i am a ringer, i ran this in college, that whole psychological complex, it's, yeah, i ran in college but nothing like this. run single mile races or marathons if you did then 5k/10k. or run 10ks if you ran mile. you might still feel some ego pangs but it's tapping into something new so why feel awkward. i haven't run this event any more than the average joe showing up. i am just good at running. why should i be ashamed of that. particularly if you build it into running other things on a bigger stage. maybe run 5th avenue mile where you get a little humble pie in some other space.