I guess I can't hold it against LE for still offering/conducting them, but polygraphs (personally) mean nothing to me, more or less. I know LE swears they use them to "help weed everyone out", but also it's pretty well-established that they're borderline meaningless, which is why they're not allowed as evidence in anything that counts for anything.
So. If they're giving people polygraphs, good for them, I guess. I hope it gives them data they can use. To me this just means they don't know for sure who did this and are hoping to stress someone out enough to make a mistake (totally reasonable and fair; also has NOTHING to do with whether or not polygraphs work as claimed).