How much risk am I putting myself in by using designs coming into the public domain?

I want to use the Rider-Waite tarot deck designs in some of my own products that I would be selling. If you scroll down to the "Copyright status" section you'll see what I'm worried about. The designs were made in 1909, and should fall into the public domain. However, the company U.S. Games Systems is trying to claim they actaully own the copyright until 2021, claiming 70 years after the authors death even though that should not apply. Here is another article on the subject.

It sounds to me like the company may just be potentially overly litigious to protect their golden goose. I'm curious if someone more seasoned than me could explain if there is actually a lot of risk here. Is it likely that a company could try to take me to court for using their clearly outdated copyright? Would they have a leg to stand on? Would it be worth just waiting until 2021? I'm just trying to get my ducks in a row before making any potentially risky moves.