Question: Why did they hide the hole from 1953?
About the article "Union Station (Washington, D.C.)", section "1953 overrun".

Candidate passages:
Mathew and Susairaj had repainted a wall to hide the bloodstains.
Malad police did not ask them why one wall was coloured differently from the rest. 
The Blood Hole massacre occurred at Middle Creek 6 – 7 miles from Glengower Station between Clunes and Newstead at the end of 1839 or early 1840 killing an unknown number of Aborigines from the Grampians district who were on their way home after trading goods for green stone axe blanks which they obtained near what is now Lancefield.
After an initial period of establishing Glengower station where Captain Dugald McLachlan's employees gave out flour and sugar rations and sometimes employed the local aborigines from the Dja Dja Wurrung (Jaara people).
Why the massacre took place is not recorded, although there is some speculation as to why.
The massacre happened after the station hands found the cook hanging from a meat hook near the kitchen at the end of the day and the aborigines who had passed though on their way home were found at Middle creek, a camping place on the aboriginal trading route from the grampians to the greenstone quarry at Mount William near LancefieldThe aborigines were found at the waterhole on Middle Creek west of Glengower Station.
The aborigines sought to hide by diving into the waterhole where they were shot one at a time as they came up for air. 
The Ferrers appear to have remained Roman Catholic recusants after the Reformation, along with many other members of the Warwickshire gentry.
They sheltered Catholic priests, who were under the threat of a death sentence if discovered, and made special provision to hide and protect them.
Several priest holes were built, secret passages to hide people in the event of a search.
One hole is off the Moat Room, and is simply a small room with a door hidden in the wood panelling.
A second leads into the ceiling, and though not visible to visitors, is reputed to hold six people.
A third is hidden in an old toilet.
Fugitives could slide down a rope from the first floor through the old garderobe shaft into the house's former sewers, which run the length of the building, and could thus probably hold at least a dozen people.
These priest holes are said to have been built by Saint Nicholas Owen, a lay-brother of the Jesuits who made many masterful hides, notably at nearby Harvington Hall.
He was eventually caught and tortured to death by the Protestant English government.
The hides came into use at least once, in 1591 when a conference of Jesuit priests was raided by local authorities.
They did their job, as no-one was caught.  
While not a formal concept album, many of the songs still have common themes related to serial killers, youthful innocence gone wrong, and criticisms of the modern world.
The album's title is also ties into this, with the phrase being Latin for "in absence" or "in one's absence", often in reference to a person's rights when mentally unable to be represented in court in legal situations.
Wilson said of the title: "It comes from…it's related to some of lyrics.
It's about people on the fringes, on the edges of humanity and society.
I have an interest in serial killers, child molesters and wife beaters…not in what they did but in the psychology of why, what caused them to become unhinged and twisted?
Why are they unable to empathize?
It's Absentia sort of a metaphor - there's something missing, a black hole, a cancer in their soul.
It's an absence in the soul."
Certain clauses of adverbial character are also sometimes classed as relative clauses: those qualifying a noun, normally replaceable by a similar standard relative clause: "the place (where) I live" (i.e.
"at/in which I live"); "the reason (why) we did it" (i.e.
"for which we did it").
those functioning analogously to free relative clauses, but in an adverbial role: "I won't hide where you hide"; "I'll do it how(ever) you do it."