Q:

Why 皮切り is labelled as a sensitive word in the dictionary? 

When I studied Japanese this morning, I found this word 皮切り in my dictionary:
Example sentence:
それを皮切りとして欧州の詩や文学を多数紹介するようになりました。 
Translation: With that as a start many European poems and much literature came to be introduced. 
From the example sentence, I don't find the usage 'sensitive'. 
Sources:
https://jisho.org/search/%E7%9A%AE%E5%88%87%E3%82%8A
However, after some research, I find this to be interesting:
Opinion of user1

http://www.edrdg.org/jmdictdb/cgi-bin/entr.py?svc=jmdict&sid=&e=1118327
最初に据える灸は皮膚を切るような痛みを感じることから。包茎手術の意はないが卑俗に感じる場合もある
Basically it's from the two Kanji used that give the feeling of "cut
  skin". 
My guess: This word is related to a circumcision, thus labelled as
  'sensitive'. 

Opinion of user2

I have never thought of 皮切り as a sensitive word.  I use it, people use
  it. 
It seems that some publisher put this word on their list of sensitive
  words at some time because they thought it might remind the readers of
  circumcision, and therefore might sound vulgar. 
In my opinion, it's far-fetched.  Again, people use the word. 

Opinion of user3

There are lots of words to do with cutting, leather, flesh, and
  butchery which might have connotations that moderns no longer feel. 
https://en.wikipedia.org/wiki/Burakumin
Note that Entertainers were even below them, considered non-human,
  whereas Burakumin were cast out, but still considered human.  It gives
  more context to "The Izu Dancer", that. 

Additional information:

In JMDICT history: This word seems to be included in
  放送禁止用語 or banned words in TV.  It's on the NHK list of things to be avoided or used carefully.  It seems it can be confused with
  circumcision. 

My questions:
1.Are their opinions correct?  I mean that the reason of the word being sensitive?  Why do you think so? 
2.What do you feel when using the word i.e.: 皮切り, is it truly sensitive to your native ear? 
3.One of the meaning is 'beginning with/starting with' and I think it's pretty neutral.  Is this correct? 
Thank you very much! 
Source2

A:

I am not sure.  皮切り derives from the usage in 灸, and my monolingual dictionaries do not have any relevant information (about its being sensitive).  I don't really imagine it can be incorrectly linked to circumcision.  I was not able to verify that it is prohibited on TV at all. 
It is never sensitive for me.  In fact, it is often used in news, including NHK. 
It is neutral.  

Some usages:

１６世紀、太閤・秀吉が進めた城下町の開発を皮切りに、江戸時代から急速に水運が発達した大阪 --- NHK
日本勢は清水宏保がスケート５００ｍで「金」に輝いたのを皮切りにメダルラッシュ --- Yomiuri
ソチ五輪の競技始まる　スノボ男子予選を皮切りに --- the title of an article from 日本経済新聞
昨年2月に岩手県で開会式典が行われたのを皮切りに， --- 文化庁
上海の百貨店を皮切りにテナント展開 --- JETRO, Japan External Trade Organization

As you can see, many sources with status uses the expression.  It being sensitive is a minority view, if not an urban legend. 

A:

I didn't know 皮切り is a word that is not allowed to be used on the air.  If that is true, they may think 皮切り make people think of circumcision.  I don't think of any other reason. 
I don't feel anything unnatural about that. 
皮切り is sometimes used as the meaning of "beginning with/starting with", especially in news or written language, though it is rarely used in daily conversation.