It's essentially a FUD campaign, or so it seems to me. Compare it with the SCO case. SCO have said that some mysterious code of theirs has been copied, but they won't tell anyone exactly which lines of code, which sections of Linux it affects, or indeed anything at all useful. They're just dangling the spectre of copyright infringement, particularly worrying to American companies at the moment, with that DRM, RIAA, MPA, etc, nonsense forever in the press, in the hope that companies, especially small companies, get scared and either buy the SCO build of Linux (which is, by all accounts, rubbish) or pay a licence fee.
Tulip seem to be doing the same thing. I'd guess that their aim is to scare the smaller sites and emulators out of existence, as they wouldn't be able to afford to fight a lawsuit (hands up everyone who's registered a C64 emu. Anyone?). They remove the competition, and so C64 fans have no choice but to buy the "official" emulator. For larger sites, they'd just need to win one court case for most of them to start shutting down too.
Hmm... I wonder what Gateway would say if they knew that Tulip, in writing a commercial C64 emulator, were trying to make money out of the C64 hardware IP?
Perhaps if the C64 scene rallies around and convinces the original games programmers not to sell their games to Tulip they'd have to reconsider their new scheme. However, I think enough copyrights or licencing rights must still lie with the publishers (who tend to want to exploit IP as badly as Tulip seem to) for Tulip to put together a large catalogue of licenced games.