It's a very narrow ruling, conditioned on the fact that the defendant, Hancom, publicly acknowledged they were using Ghostscript under GPL. It does not say much, if anything, but IANAL, about a defendant who would not have acknowledged this, which seems like the more interesting question.
Common law judges are very prudent in their ruling.
The defense argued that the license was not enforceable. In the order, the federal court laid out the reasons the license _is_ enforceable. Here's the order:
Defendant (Hancom) was trying to say that because they didn't sign anything they didn't have a contract.
But Hancom "represented publicly that its use of Ghostscript was licensed under the GNL GPU"
Therefore, the Judge ruled that in their own words they publicly acknowledged the contract.