problem with choice of case in First Greek Writer

[NateD26]

in First Greek Writer (Arthur Sidgwick, Third Ed. Revised 1883) under §53. Relative & Participle
the author demonstrates the difference between a relative clause that's "practically belongs to the predicate"
and a one that stands as an attributive to the subject.

my problem is why did he change the case of νόσος from acc.sg, to gen.pl. in the attributive relative clause?

if "who was ill" = νόσον ἔχων in the first sentence, why it is changed to "ὁ νόσων ἔχων" when attributive?

[modus.irrealis]

It's a typo. It should be ὁ νόσον ἔχων.

[NateD26]

Thank you.