We are kicking explinations back and forth.
The Old Earthers would say that The Hebrew word YOM, (yôm) can refer to some unspecified period of time, as in "the day of the LORD" which is seen in Amos 5:18 as one example.
Deut. 32:7 says........"Remember the days (Yom) of old...".
AGAIN.....I am not suggesting one meaning over another, but think.......
So, how long is a day? We cannot say that a day is by necessity 24 hours. And therefore we also cannot say that a yom is 24 hours either.......... Especially since the sun (or "greater light to rule the day") was not created until the fourth day (Genesis 1:16).
In other words, it is dangereous to offer an interpretation, especially of Scripture, that expresses the our own ideas, bias, or the like, rather than the meaning of the text.
To insert the meaning of "24 hours" to the word "day" (even in English), since even in our present time, it is not so. We say a day is 24 hours out of convention and pragmatism (imagine if we started using strict sidereal days or solar days, the mess that would create), not any other reason.