Enter the rock and hide in the dust are descriptive phrases for run and hide. Hide in the caves, crawl into a hole, get down into the dust and blend with the dust such that you cannot be seem, hidden from view, out of sight from discovery.
Because of the previous verses.
For the person who has ignored God, doctrine, and his spiritual life as God has defined it.
For the person who has chosen to pursue the world and its pleasures, its beliefs, its views, its conveniences, its enticements, its compromises.
For the person who has decided to pick and choose which principles they will or will not abide by.
For the person who has no respect for God and truth.
For the person who does not fear God.
Then here is the warning.
Judgment, discipline, corrective action are coming, sure as you are reading these words right now, sure as the sun will come up tomorrow, sure as anything can be sure.
For God has but one answer to any and all rejection of truth, all of which rejection only leads to trouble and suffering and pain for all, sooner or later.
Life in this world is temporary at best. Life in this world only provides you with a logistical mechanism to get by, while giving you an opportunity to grow up in your spiritual life, thus preparing you for eternity.
This is the devils world, and all who choose to rely on this world only, is in for certain trouble, and trouble will come.
Therefore if you are to respect anything, at least respect Gods wrath as it approaches and overwhelms your life.
But where can you hide? Nowhere.
Hide in the rocks, or in the dust for what good it will do you. You cannot hide in your success. You cannot hide in your titles or credentials. You cannot hide in your beliefs or attitude. None of these things, nothing of this world, will be able to deflect or stop Gods assault when it comes.
And Gods punishment does not have to come with overwhelming power and force. It can come into your life with a slip in the shower, with an accident on the road, with a choke of a piece of food. And certainly His wrath can come by means of an invading army made up of man or disease. God has no shortage of arrows or methods with which to straighten out your life, after you have strayed off the path of truth.
And in each and every case, it will not be God who will be the bad guy, but His righteousness and justice will be magnified as right and true and correct and fair.
Gods glory and majesty are never tarnished. Only mans glory gets placed in its rightful place, in the dust, from whence it came.