My take on it is it's a totally different platform (a preamp module), so all Anthony is recreating is the
tone (or his interpretation of it, at least) of the amps he bases these modules around, and potentially some of the features (like the dual gain knobs). I don't think the tone or the features are trademarked, which is why modelling companies can create their takes on these tones, too, but with slightly different names.
I am sure someone with more legal knowledge than I have could chime in more on this, but I think a less scrupulous amp builder could probably actually build an exact replica of an amp (power section and all), perhaps with very minor changes; call it something different, and sell it without legal issues. I think copying the trademarked items is where someone could potentially get into legal issues with this. The practice of imitating tones has been around for quite awhile, so I imagine if it were illegal in any way, the practice would have stopped some time ago.
Quick add: I agree a bit with fuzzboat, Kapo. You make some (IMO) somewhat inflammatory remarks, then minimize it by saying you're cool with it. I am under the impression that you're well aware this is going to cause some conflict. This is hardly a new topic, so I have to wonder what you're motivation is for making your comments. Too much treble? Or maybe not enough?
That said, I can't wait to get my Rhoadie and Camerock!