It was a real world theory before it was a science fiction theory.
By 1947, people were wondering if the devastation shown by the 1921 expedition had been a nuclear blast. One of the goals of the 1959 expedition was to check for signs of a nuclear detonation - they couldn't rule out a clean fusion bomb, but were able to rule out a fission bomb based upon then current tests - the damage was too large for a fission bomb to be the cause.
It wasn't until the 1970's that a nuclear detonation was ruled out, due to isotopic analysis showing a lack of radionuclides from either fusion or fission, but fusion as a mechanism is often broken out as an explanation.
Given the mix of incredible high force, low radionuclide, airburst detonation, and particulate deposits, prior to the Shumaker-Levey 9 impacts with Jupiter, there was little evidence that asteroids and comets could airburst. After, it was far more credible. And recently, an asteroid detonation with particulate fallout and airburst explosion was observed in the Chelyabinsk meteor event.
Before these confirmations of blast wave and detonation, the primary theories were some massive airburst bomb of unknown mechanism, asteroids, comets, and extraterrestrial craft with an engine detonation. Some sources claim the alien explanation was floating around in 1947...
Any dismissed theory is grist for authors imaginations; phlogiston theory has been resurrected in recent years with Steampunk literature. The only two particularly plausible theories are an alien ship or a meteor detonation, and the evidence is most strongly in favor of the latter, because "there's no proof of aliens."
So, while broadly dismissed by science, it's still a plausible theory, and one that has half a century of scientists preaching it.