Tim and James are correct. Not only does the Hebrew and Greek vocabulary have a broad enough semantic value to predicate both saving favor and non-saving favor. The semantic range of the English term "grace" is broad enough to include saving favor and non-saving favor. So there's no linguistic or biblical basis to stumble over the terminology or concept of "common grace." Those who argue that the term "grace" must be reserved for salvific favor commit the same fallacy as those who argue that the Greek term agape refers exclusively to godly or noble love.
I think these men are saying something more along these lines:
The term "grace" is normally used in Christian theological discourse in such a way that it brings to mind a salvific favor of God through Christ towards sinners who have demerited this favor. We are against the terminology of a common grace because it will cause the confusion of theological categories in an unbiblical manner.
Other godly Reformed theologians have thought along a similar vein. For instance, Abraham Kuyper, although certainly an advocate of a common grace of God, nonetheless distinguished so sharply between common grace and particular grace that he actually used different Dutch terms for each! Michael Horton and other contemporary theologians oppose the use of "grace" to describe God's relationship to man prior to the Fall for the same reason. These men are not so ignorant as to be unaware of the semantic range of the different Hebrew, Greek, and English terms. They are rather consciously recognizing that theological discourse necessarily creates categories narrower than a term's semantic range which may prohibit otherwise linguistically legitimate use of term.
In other words, a Protestant Reformed theologian would probably acknowledge that you
could speak of a common "grace" if you added the qualifications that such a "grace" was no more than presently apparent to the reprobate (ultimately further damning them) and that this "grace" in no manner represented a desire within God to love/save the objects of said grace. However, is such a use of the term really prudent and wise? Protestant Reformed theologians point to the history of "common grace" in the last century and answer with a resounding "No!" I tend to agree with them.