WASHINGTON — President Trump and his allies insisted Saturday’s shooting at the White House Correspondents’ Dinner proves the need for his planned über-secure White House ballroom . Since 1968, the celebrated dinner has been held at the Washington Hilton, a hotel complex about a mile and a half north of the White House. But due to the fact that it’s a hotel, suspect Cole Thomas Allen was allegedly able to book a stay and sneak weapons there. That’s why Trump and his allies believe a secure ballroom facility is needed at the White House. The president has long pushed for a White House ballroom with advanced security arrangements. Getty Images “What happened last night is exactly the reason that our great Military, Secret Service, Law Enforcement and, for different reasons, every President for the last 150 years, have been DEMANDING that a large, safe, and secure Ballroom be built ON THE GROUNDS OF THE WHITE HOUSE,”  President Trump posted on Truth Social .…