Picard says it's because they were killed in a fantasy created by Q. Should that really make any difference?
I would tend to think so. In the first case, Riker was simply reversing another god's created fantasy.
That's a bit different from reversing a death that occured in the natural world, from a natural event. There were probably a bunch of other colonists who died from one cause or another over the years too. Should Riker bring every one of them
back to life too?
I think most people would probably think that would be wrong and unnatural.