"However, do you really think it took 10 minutes for the cabin crew to intercom the pilots and say...we have injuries back here.?" PTH
I'm just going by the radar track - for whatever reason, the flight did not deviate off course (and towards Denver) until about 200 nm past the reported location of the upset.
I suppose the crew may have made the decision earlier and was just staying south to avoid that long line of storms (a pretty impressive demarkation of the "dry line," BTW) - the same line that ends in a big patch of red right over KMCI. Their eventual path to KDEN goes through/over the thinnest part of the line.