Interesting thought, but that would take (1) some really hefty vibrations + (2) some really old, fragile wire. Like we're talking 100 yr old + cloth wire for that to happen in my opinion.My guess it the data cable is newer than the conduit and a data cable installer might hasve tried to widen that hole and somehow the vibrations combined with age shorted a wire in the conduit, and the conduit is now hot.
Would a bond directly to building steel in the area work?The first thing I would check is that data cable to see that it isn't damaged where it goes through the hole. There absolutely should not be any kind of voltage on that cable that would cause sparks and flame but you never know what somebody might have done.
The other thing (more likely) is that the conduit is contacting the rebar or reinforcing wire in the slab on the inside of the hole. Both the conduit and the rebar or reinforcing wire should be bonded to ground but It's been my experience that there still can be a considerable potential between the two. So, make sure the conduit is bonded back to ground but I'm open to suggestions on how to bond the reinforcing in this situation, short of breaking up the slab to expose it.
I don't think this had anyhing to do with the cleaning people spilling cleaner down the hole other than in trying to stop it from running down and cleaning it up they may have stuffed a rag down the hole which moved the conduit. So really, you should thank them for exposing what might be a serious situation.