well, this is exactly what is not to do! this is the perfect example of copyright infringement... generic means not resembling anything existing, under copyright... or resembling everything existing without any copyright! wich is the easier thing to do? (if you don't want to be sued?)
I'd doubt whether Caesar's Star Wars sets were produced without license, as they even had the name Star Wars on the box. Doing something like that would have been a quiten brazen undertaking. If indeed they did that without license this might be a reason why they are out of business. But I don't think they were that stupid.
I would have thought it would be quite easy to make a sci fi range without impinging on copyright, certainly, lots of metal manufacturers seem to be able to do it without problem. As far as I know there is only one set available and although I rather like its 1950s feel I can imagine that it wouldn't be to everybody's taste.