The reason why he believes only those two could break the mountain, is because those two are the only one "that person" probably loves with his heart
Sometimes hacking the mountain into two is not the only way to break it. Sometimes it could even be whittled down by raindrops.
If the raindrops are heavy enough and long enough, even a mountain would be whittled into stones and dust.
Sangmin did not emanate his aura out.
But his scepter did not shake and his forehead did not sweat.
He just calmly sitting there and look at the heavens with indifference
In the world during the absence of Death Monarch, there is many people that heard the rumor that those Twin Sages of Japan had reached Divine Comprehension.
Some said the Earthshaker of the World Government had reached Divine Comprehension and is considered a trump card of the World Government hence he rarely takes actions nowadays.