On the terminology side: language is about communication, and there is a broad consensus on the meaning of "free" in terms of free software, exemplarized by the FSF's defnition, the OSI open source definition, and the DFSG. None of these definitions is identical to the others, and no doubt there are edge cases that would fall under one but not another, but neither the GPL nor Crockford's license is one of them; under this consensus meaning of "free" (which you claim not to be arguing about), the GPL is a free license and Crockford's is not.
On the practical side: the GPL is established and popular enough that you should know what you're getting yourself in for with GPL code. In theory I can imagine someone unfamiliar with the free software movement hearing that a piece of GPL code was "free" and assuming that meant they could use it in their closed products, but in practice when people talk about "free" software they tend to either mean the free software definition, or "freeware" (i.e. binaries which can be downloaded without charge) - which generally doesn't permit modification and redistribution. So I don't think this is a practical concern.
By contrast Crockford's license is not popular or established. Worse, it looks exceedingly similar to a popular, established license - the MIT license - which is free (in the free software sense). So it's very possible to accidentally download a Crockford-licensed piece of code, thinking that you can use it in a free software project, when in fact the license does not grant all the rights you would need to do this - as is demonstrated by the fact that the author of this post did exactly that.
Crockford is free to distribute his code under whatever license he likes, but using a license that looks very much like the MIT license but grants you a much smaller set of rights (a set which puts it on the other side of a line that, while in many ways arbitrary, is of great practical relevance when it comes reusing code in the wider internet community) is not nice.