bidnez wrote in linguaphiles

German punctuation question

"Der Philosoph behandelt eine Frage; wie eine Krankheit." - Ludwig Wittgenstein, Philosophische Untersuchungen, §255

is translated by G. E. M. Anscombe as:

"The philosopher's treatment of a question is like the treatment of an illness."

My feeble take is:
The philosopher treats a question; as an illness.

As I understand it, two independent clauses without a conjunction in English usually require either a semicolon or a period, while a comma can do that job in German. This would mean the rules governing semicolon usage in English could be broader than they are in German. Only the first clause is independent here though.

My questions:
What does the semicolon do in German that it might not in English?
Is the structure of the sentence unusual (or even "incorrect") in German?
And more conjectural: Why might the semicolon have been dropped in translation?

Any information is appreciated.