Even worse, there's a reason GPL isn't tested in courts. Because it's so rock-solid companies who violate the GPL realize going to court will cost them big. So they settle rather than head to certain failure.
GPL basically says "you have certain rights under copyright. We will grant you additional rights, but you agree grant the same rights to those who get your code. If you don't you don't have a license." Those who violate the GPL end up violating copyright without a license.
The fact that no companies are willing to test it in court signifies to me the strength, not the weakness.