It almost sounds like they've set their minds on letting the system die. I think this would help in a legal battle.
Regardless, everything in Frog Feast is 100% legal. I don't have access to any developer docs, and defintely don't have an SDK or development kit.
I have plans for a few more products for the Neo Geo CD. It is probably one of the easier systems to develop for. The Sega CD can be pretty finicky, but the Neo Geo CD seems to run anything thrown at it.