There are multiple ways to unfold a box into 2 dimensions. For example, see this printable pattern that you can try at home [1].
Also, how else would you determine the distance between two coordinates in a plane without using the Pythagorean theorem [2]? It's not like he could use a measuring tape in an imaginary, unfolded room.
EDIT: I reread your post and see that you are pointing out a typo. The phrase "one-dimensional surface" was obviously meant to be "two-dimensional surface." A one-dimensional surface is non-sense.
Also, how else would you determine the distance between two coordinates in a plane without using the Pythagorean theorem [2]? It's not like he could use a measuring tape in an imaginary, unfolded room.
EDIT: I reread your post and see that you are pointing out a typo. The phrase "one-dimensional surface" was obviously meant to be "two-dimensional surface." A one-dimensional surface is non-sense.
[1] http://familycrafts.about.com/cs/coloringpages/l/blboxtempla...
[2] http://www.purplemath.com/modules/distform.htm