I'm not even debating if the city that was found can or can't be the biblical Sodom. That remains to be seen. However, the idea of an asteroid fly-by over the area (finally crashing on Köffels valley in Tirol, Austria) that caused fire and brimstone to storm the Dead Sea area and that clay tablet making reference to such event has been entirely debunked as pseudoscience.
No one has yet come up with a plausible reading of what is written in that tablet. To claim that it makes reference to an asteroid observation of 5000 years ago is nothing more than speculative wishful thinking.
Look up the article "Fire In The Sky", by Jeff Medkeff and Martin Rundkvist published on February 4, 2009 at skeptic.com
Eden