What I can see is just about word vs word, there's no clear evidence about the proof chat which from Small Rabbit since it's already been deleted. And Small Rabbit is blaming the developer according his story, the developer tried to scam him. Of course it's will hard to prove which is wrong between them.

I can't say it's a scam, but it's more like not professionalism when handling the campaign since the reward pool is suddenly changed as he want. However the reward pool should be fixed first before starting the campaign, so it wouldn't hurt anyone.