Kind of.This person usually does not say much, but when he says something people get astonished.
Is that it?
Need confirmation. Thanks.
It derives from an idom 不鸣则已，一鸣惊人.Hi,
Another difficult expression :
No clue whatsoever except that 李远哲 is someone's name.
It derives from an idom 不鸣则已，一鸣惊人.
It means, (he) was just mediocre for a long time, and then suddenly, his action impressed all (in a good way).
李远哲 is a Nobel prize winner, and gets involved in politics in recent years, and his political views are very controversial. So, in this context, 不鸣则己，一鸣吓死人 has a negative tone.
吓死人 - scares people.
My understanding: Mr. Li either remains quiet, or airs something ridiculous.
(Don't take it personally. Just my understanding to this sentence. No offense to him.)
This sentence should be written by someone against his political view.