No, no, pretty sure this is real. In the game PoFV I do recall Aya saying something about not liking to do articles about people dying or taking their lives. I think, it's just she's more disappointed that is happened to someone she knew that she thought was strong.
Allaire said: I don't think Aya would really say such cruel words. Maybe it's just another Marisa's delusion?
Aya is actually that cruel or at least her words sound that cruel. In SSiB, when everyone but Reimu returned from the moon and people were starting to wonder if Reimu had died, Aya just commented that it looked like they would need to get a new Shrine Maiden soon and that she hoped it was someone who would generate lots of stories for her to write.
Canon Aya comes off as something of a self-absorbed b*tch (though, given her age it could just be that she has lived for so long she simply no longer cares about anything that doesn't provide her with some entertainment/stimulation), she is canonically a blatant liar, and she is also a suck-up (at least when it comes to the oni). As annoying as she can be in fanon, in canon she's actually worse.