Meaning clarification about「扱う」and 「禁じ手」 in this sentence

Question

The parts marked in bold are what I am unsure about in this sentence...

「すでに敵対組織はかなり掃討されたのに、麻薬の流通量がちっとも減らないのは、謎のボスが禁じ手のはずだった麻薬を扱いだしているからなんじゃないのか、と思うんだが...」

The dictionary entries of 「禁じ手」usually are limited to 'unallowed moves' or fouls in sports; however judging from this sentence I believe it can mean something like 'taboo' as well. Furthermore I was struggling with understanding 「扱いだして」but I think it means something like 'starting to sell/handle/etc.' here.

In short my questions are whether my understanding of above-mentioned is correct or not.

Answer 1

You have basically answered your own questions, so I will be brief.

"Taboo" is an excellent translation for 「禁{きん}じ手{て}」.

The 「手」 in this word originally means "a move or technique" used in sumo, shogi, go, etc. 「禁じ手」, therefore, originally refers to a prohibited technique or move in those sports and games.

The 「だす」 in 「扱{あつか}いだす」 is 「出す」. When 「出す」 is used as a subsidiary verb, it is often written in kana and it means "to start ~~ing".

Answer 2

You are absolutely right.

「禁じ手」usually means 'foul play' in sports. But in this sentence, it is used as a metaphorical expression. 「扱う」has the closest meaning to "handle" in this sentence.