I highly doubt they'd roll out a separate leaderboard for the cheaters. I mean, the reason they introduce those DLC is because they badly need some money to keep their business running, so if they separate the leaderboards, who's gonna buy the DLC? That kills the point of bringing DLC.
The only thing we can do is to tweet them saying it's not cool at all and we as their fans feel disappointed by their greed. I'd keep supporting their games if they separate the DLC leaderboard, otherwise I won't buy any more Cave games unless they're on sale and certainly won't recommend them to my friends again.