No one said that KABOOM! was a reference to the origin of The Collector himself, but rather the looks of the building representing who the Collector is:
"As Tower of Terror is overhauled into Mission: Breakout, the exterior is being altered from a 1930s-era hotel into an ornate sci-fi structure befitting the Collector, who Rohde described as “an arrogant, proud, glitzy kind of figure.” That’s raised eyebrows among some Disneyland aficionados, given the building no longer matches any of the setting around it in California Adventure, but Rohde said that was very much part of the intended scenario.
“The [Guardians] world terminates and terminates very abruptly,” said Rohde, regarding the building standout from its surroundings. “That’s part of the whole ‘kaboom’ of this."
http://www.ign.com/articles/2017/01...e-looks-to-offer-a-lot-of-fun-for-marvel-fans