Use of Double Negation

Lately while trying to pick up some basic Italian, I started recalling my English grammar again. (Seriously, I fear my English is inadequate because a day earlier, I had been watching an ex-Miss Earth (Singapore)'s interview and had thought her performance acceptable despite my friend's emphasis on her Ah-Lian accent and bad pronunciation... and so to really understand where he was coming from, I chose the winner's interview and ... I was totally blown off by this young lady's command of English, mannerism and accent. It was a stark difference and I suddenly felt ashamed of my lack of good English and poor command of Mother Tongue.) Times like this, I hate to learn another language because I feel I ought to spend more time with my basics first.

Anyway I had digressed from the topic. Back to English. As I started to observe more carefully the English structure once again, I came across this writer's usage of double negation 'he has contributed in no insignificant way to Singapore politics'.
Source: ST Forum

At first glance, people will read it 'as in no siginificant way'. Because the usual crowd does not see double negation as a norm. But I had taken a double take on it, and was wondering was he praising or demeaning the person. And so I asked XX why did the writer chose to double negate the words?

His answer and a further wiki search enforced that double negation is used to emphasis your point e.g.

Standard English can use the form "I do not want nothing" as a way of emphasizing that the speaker would rather have "something" than "nothing" at all.

Let's fast forward to modern days..

Today, the double negative is often considered the mark of an uneducated speaker, but it once used to be quite common in English, even in literature.

But this writer is a ST writer and thus I trust his command of English is perfect for the job. So why did he chose double negation?

This is where the second example highlighted in wiki search comes in:

Similarly, the phrase "Mr. Jones was not incompetent" may be used to mean either "Mr. Jones was very competent" or "Mr. Jones was competent, but not brilliantly so."

I may have been overly cautious towards the writer's choice of words or he had indeed written it in a style so that he will not be seen blatantly supporting an opposition (and breaking his steel rice bowl).

Anyway his article is proof of how mankind made full use of the wonderous English language with its intrinsic meanings. And for that record, his focus on the article was definitely not on that line but as usual, I liked to see things in a different light.