Some young earth theorists, including Jonathan Sarfati in his book Refuting Compromise, have addressed this verse in Zechariah an Hosea. Although his argument sounds impressive, you have to recognize it for what it is...he is arguing for his young earth agenda, thus any rules that he espouses must be examined by true Hebrew scholars who are impartial. Hebrew scholars do not recognize this fabricated rule.1
What Sarfati thinks is not important...what is important, as Dr. Walter Kaiser points out, is the intentions of the author. We should not create rules that support our own agendas, but should strive to understand the author's intended meaning outside of rules.
http://www.oldearth.org/word_study_yom.htm
Yes, your link supports the argument that one can understand yom to mean an "Age" or an "unspecified duration of time:"
Strong's Exhaustive Concordance of the Bible (symbols omitted)
from an unused root meaning to be hot; a day (as the warm hours), whether literal (from sunrise to sunset, or from one sunset to the next), or figuratively (a space of time defined by an associated term), [often used adv.]:--age, + always, + chronicles, continually (-ance), daily, ([birth-], each, to) day, (now a, two) days (agone), + elder, end, evening, (for)ever(lasting), ever(more), full, life, as long as (...live), even now, old, outlived, perpetually, presently, remaineth, required, season, since, space, then, (process of) time, as at other times, in trouble, weather (as) when, (a, the, within a) while (that), whole (age), (full) year (-ly), younger
Hebrew dictionaries attest to the fact that the word Yom is used for anywhere from 12 hours up to a year, and even a vague "time period" of unspecified length.
So the issue is choice.
Those who have chosen to oppose the correspondence with the Geological Time Clock and ignore that the 24 hour day, seasons, and years did not appear In the beginning will insist the context implies 24 hour units.
But the wise who shall understand"that science and facts are powerful supports for Genesis when yom is recognized as corrsponding with the seven durations that are historically recorded in the rocks.
BOTH will claim they are following the words that god wrote in Genesis.