Intellectual property laws are ... well, confusing is probably the most polite way to say it. The last thing I remember hearing regarding copyrights was "life of the creator plus 50 years". Patents are a whole different thing, but are renewable for... I forget how long.
Since almost everything in this mod'n world is now created by more than one person, the "life of the creator" becomes a very muddy issue. And it probably got even muddier when software moved out from under the umbrella of patent law and under copyright law. (Stupid since most software will be obsolete WAY before either a patent or copyright would expire.)
Hopefully your query reaches someone at the publisher that actually knows the answer to your question. My guess is that (correct or not) they'll tell you it's protected, and the design will simply fall into The Abyss. Happens all the time.