Have you actually read the essay to which you're linking?
>Meanwhile, much murmuring has been going on in recent months to the supposed effect that the absence of judicial enforcement, in US or other courts, somehow demonstrates that there is something wrong with the GPL, that its unusual policy goal is implemented in a technically indefensible way, or that the Free Software Foundation, which authors the license, is afraid of testing it in court.
(implying it has never been tested in any court)
>We do not find ourselves taking the GPL to court because no one has yet been willing to risk contesting it with us there.
(Explicitly stating it has never been tested in court)
>I have assisted free software developers other than the FSF to deal with such problems, which we have resolved—since the criminal infringer would not voluntarily desist and, in the cases I have in mind, legal technicalities prevented actual criminal prosecution of the violators—by talking to redistributors and potential customers.
And lastly, the money quote. In the cases of criminal, malicious infringement, they were not able to prosecute.
Your implication that "untested in court" means "likely unenforceable" is quite wrong--unless you see lots of people openly violating a license in cases where it would be economic to pursue them, the more likely explanation for "untested" is simply that the accused infringers get competent legal advice, and comply without wasting their money on a losing court case. Though as other comments note, since the writing of that essay someone (D-Link) finally did refuse to comply without a court order, at which point Harald Welte took them to court and D-Link indeed lost.
And what do you think "not able to prosecute" means? District attorneys (or non-USA equivalents) decide when to prosecute crimes, not private copyright owners. It's very rare for the criminal justice system to intervene in complicated white-collar stuff, especially when a straightforward civil remedy is available. A legal realist might say that means the GPL--and indeed most copyrights beyond those infringed by warez/torrentz sites--is effectively unenforceable criminally, and would in a useful sense be right; but it's enforceable civilly, so no one cares much.
>Meanwhile, much murmuring has been going on in recent months to the supposed effect that the absence of judicial enforcement, in US or other courts, somehow demonstrates that there is something wrong with the GPL, that its unusual policy goal is implemented in a technically indefensible way, or that the Free Software Foundation, which authors the license, is afraid of testing it in court.
(implying it has never been tested in any court)
>We do not find ourselves taking the GPL to court because no one has yet been willing to risk contesting it with us there.
(Explicitly stating it has never been tested in court)
>I have assisted free software developers other than the FSF to deal with such problems, which we have resolved—since the criminal infringer would not voluntarily desist and, in the cases I have in mind, legal technicalities prevented actual criminal prosecution of the violators—by talking to redistributors and potential customers.
And lastly, the money quote. In the cases of criminal, malicious infringement, they were not able to prosecute.