why?
Basic hygiene really. Frozen meat out in hot weather will be teeming with bacteria and flies in no time. I don't see anything wrong with giving very small bits of frozen meat you'd know they'd eat pretty sharpish, just not large parts/whole rabbit that would be lingering about in the heat growing god knows what all over it.
I understand that its best to keep the meat fresh as possible when feeding, but leaving it in there for a day won't hurt. You don't see wild animals passing there nose up because it's got a bit of nose to it.