No it is not.
Exodus confirms that a Genesis day is 24 hours.
20:8 Remember the sabbath day, to keep it holy
20:9 Six days shalt thou labour, and do all thy work:
20:10 But the seventh day is the Sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates:
20:11 For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the Sabbath day, and hallowed it.
Unless we are to labourfor 6 eons, or epochs or eras, or whatever you call the other thing that "day" can be understood to be, it means 24 hours here.
There is no change of definition of "day" between Job 20:9-10 and 20:11.
Exodus ties the law of the Sabbath to a 24 hour day and to Genesis in 20:11.
Also, the "day" argument is merely a variation on the appearance of age, for, in order for "day" to mean "a long time" all of the arguements used in "appearance of age" are applicable.