The fees for these small outputs are higher than the values in those outputs.
Yes that's what you need to do if you want your tx to get confirmed.
So here is what I think: The OP wanted to perform the stress test but realized that he will not be able to accumulate those dust outputs (which he before created by splitting 250 BTC up in small amounts) without spending another 250 BTC on transaction fees.
I think it's wrong.Maybe OP was just too lazy to do it himself so instead released the priv keys so that other people would do the "stress test" for him.And you know if OP would have gave me the keys I would have got at least 100BTC from it.
Now he realized that he essentially burned 250 BTC and the release of those private keys is one last desperate move to reestablish his good reputation (by appearing generous). The private keys however are entirely useless.
As amaclin said useless for who?