Esco's project isn't just a hack, it's a PC remake.
And people are forgetting Mega Man 7! (and 8...) The Famicomization of Mega Man 7 is still available for download at its site, and if that ain't an "illegal fan game", I don't know what is. Capcom hasn't done anything to stop it. And Konami has yet to even try to put a halt to Castlevania clones. Komajou Densetsu II is still up for download at its site, and it's a blatant "ripoff" of SOTN. So all this "illegal fan game" talk is pointless. Konami wants people to make fan games, otherwise the company will completely lose its foothold in the market.
What it boils down to is Konami won't go after fan games unless there's money to be made in doing so. Most fan games won't step into the realm of cutting into Konami's profits, at least in the Castlevania franchise. Yugioh was a different matter, since shutting down a free-to-play online Yugioh game meant Konami could then market a pay-to-play Yugioh online game. In the case of Castlevania, there's nothing for Konami to worry about and it might cost them more money to worry about it. Esco may be playing with fire, but he's about the only one. ... Well, ROM hax themselves are bad too, but that's not what we're talking about here.