Here are different tests, I would expect all of them to produce unsorted results.
$ printf '{"z":2,"a":1}\n{"z":22,"a":11}' | gron --no-sort -s
json = [];
json[0] = {};
json[0].a = 1;
json[0].z = 2;
json[1] = {};
json[1].z = 22;
json[1].a = 11;
$ printf '{"z":2,"a":1}' | gron --no-sort -s
json = [];
json[0] = {};
json[0].a = 1;
json[0].z = 2;
$ printf '{"z":2,"a":1}' | gron --no-sort
json = {};
json.z = 2;
json.a = 1;