confused?

Good day everyone,

Trying to understand an article from the Techno-Isel site where they
described configuration of a mill needed to machine a wing 105'x21'
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http://www.techno-isel.com/Tie/Boeing_5.html

In theory, wing spars and wing skins made in one continuous
piece..... require metal measuring up to 105 feet by 21 feet. ... A
standard CNC mill has a fixed length arm extending over a table...
the spindle would have to hang over 12 feet from the column, losing
precision and strength.
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It appear to me that a spindle overhanging 12' from the column (12'
throat) have a work envelope of only 12' in that direction? So, is
Techno-Isel confused or is it me who is confused?

A1