I don't believe that. These plants cost several billion each to build. The legal costs couldn't have been but a small fraction of the overall costs of building the plant. That sounds like a bogus excuse to me.
When a plant is being built, or has been completed, but cannot open for years because of legal wrangling, they are not making any money, thus it is a hugh cost to them. Why do you think that utility companies stopped building them? It wasn't worth it to them from an economic standpoint. It's the same reason there hasn't been a new refinery built in almost 30 years.