Pretty sure if Blackhearted wanted to make his own figure he's quite capable of doing so. He's demonstrated multiple times that he understands anatomy and he can model. Not having his own figures in the store doesn't mean he's incapable of creating one.

Sixus1 doesn't even release support content for Scarlet anymore, and hasn't for at least a year or more now. Not on this site anyway. Which seems to be a common issue with most people that try making their own figures. They stop supporting them after a relatively short time, if at all, likely due to not getting the return or interest in it that they were expecting. A big part of making a successful figure - or anything else really - is marketing and publicity. Take Ero's PE for example - he had a pretty large fan base for his figure before she's anywhere near being ready for release, because he's put a lot of time into doing his own renders of her and posting them on various sites, as well as using custom versions of her in his comics. That's marketing. And because he's using her in his own comics, that's marketing he's getting paid to produce.