[youngjim]

He's become a metaphor for the "decadence of morality" [sic] you've witnessed.

"sic" is latin for "thus", or "so." This indicates a spelling error or in this case a grammatical error. The error here is the joining of "decadence" (a noun) with the preposition "of" and another noun "morality." This usage would indicate the writer means a quality of morality is "decadence" which we can dismiss prima facie as absurd. The writer should have used "decay" of morality. "[D]ecay" can be a noun or verb in context, but in this context it is undoubtedly a verb acting on the direct object "morality".

[unspun]

dec·a·dence (dĕk'ə-dəns, dĭ-kād'ns) n.
A process, condition, or period of deterioration or decline, as in morals or art; decay.

http://www.answers.com/decadence?nafid=3

Good night, yj.