Johnson was ultimately correct in thinking that poems such as Fingal and Temora are better understood as the work-of 18 century poet (than those of/ than that of) a third century one. Is it those or that, what are we comparing here?
"The poems are better understood as the work of an 18th century poet than the work of a third century one." We are comparing work to work, so "that of" would be the proper replacement (singular).
