Yes it was donations, but it was donations collected under the conditions of doing one thing and then doing another. Just because it is a donation doesn't mean it cannot be a scam. Example, go out and collect donations to feed the hungry and then go out and buy yourself a for profit restaurant.....you will go to jail because it is a scam.
Same thing really, he solicited donations in a tear jerking manner to complete Microscash and then went out and developed himself a rather snazzy exchange.
The point being again, if the 250 BTC is a drop in the bucket for RS, then he should make a drop if it wasn't a scam.
~BCX~
Let's assume someone stole the money - go out and collect donations to feed the hungry and then get robbed on the way home, you don't really feel motivated to go out trying to do that any more, so you do something else for a while. That's not a scam, that's called life.
If anything, RS should pay back not the 250btc, but the value of the btc back then in btc. That said, it was a donation, so anything you'd receive back would be out of his good will.
If he did keep the money, and it wasn't stolen? That's pretty poor form, and he should pay back the value of the btc. Honestly though, if he were a scammer, it would be so much easier to claim option A, and pay back peanuts to shut you up so that he could continue scamming unchallenged, so chances are decent that it was a genuine tragedy that you should move on from.