In fact with the exception of Old Five who had some bad premonition about this, the others were clearly taking these words as just a joke.
But when those five words sounded through Uncle Satoru's vocal cords the whole five members of the Council turned dead silent.
They had thought that Eric's words would be some kind of empty threat towards them, but in fact, the threat was real, and more than real.
Each of those 5 words, were in a way connected to their real-life identities, something that only the five and their families knew about.
They were the columns of the country, they were the ones who kept it safe and undisturbed, and they were the atomic bombs that kept the outsiders out of their country.
They would only act when the country was on its last straits, and only when their borders or identity was threatened, otherwise they were deemed to die unknown and unrecognized.