I think the best copy protection those games have is their general unavailability and lack of interest. No way their DRM wouldn’t be cracked if someone actually gave a damn.
Meanwhile XenoCrisis peeps did not give 1 fuck about wasting time creating draconian measures against ROM dumping, and they did not sperg out and throw a tantrum over bootlegs. Whoever wanted a legit copy would buy one regardless anyway, and that’s the way it should be with homebrews IMO.