1850 CENSUS ERROR

Isaac is erroneously listed as part of the Williamson family, numbered 806/805 in the attached 1850 Census. 
They are on p.16 and he is the first name on p.17. 
The name just below Isaac's is William, his grandson (son of James H. Willoughby). 
William does not have a surname listed with him because the Willaby (misspelled) surname 
is written with Isaac who is the actual head of family here. 
Along with William, other names are Ruth (William's wife), their two young daughters 
and two females with the last name of Price.