Who knows what the FA said to the pilot. Donna Beegle keeps changing her story about the exact words said and nobody had a camcorder/voice recorder going (and if they did nobody heard it). As far as I can tell from the ATC audio to Denver Center, UA 285 declared a medical issue as the reason for diverting.
From LiveATC history:
ZDV Den-High-South-May-06-2015-0100Z.mp3
14:47 on LiveATC UA285 (does not declare name?) (07:14:47 PM MDT): change our destination to, uh, Salt Lake City,
due to a medical situation in the back.
15:11 (7:15:11 PM MDT, 24 seconds later ) : no audio, but
flightaware records as the time of diversion
KSLC-Twr2-May-06-2015-0130Z.mp3
19:15 (7:49:15 PM MDT) KSLC TWR : United 285, Salt Lake Tower, wind three zero zero seven, runway three four right, clear to land.
23:35 (7:53:35 PM MDT) KSLC TWR: United 285, turn left hotel nine, and then join hotel southbound, taxi to the ramp, this frequency.
23:49 (7:53:49 PM MDT) KSLC TWR: United 285, I believe they're, uh, waiting at the gate there for you. Did you require any other, uh, services or assistance?
23:59 (7:53:59 PM MDT) (distorted, but sounds like "negative").
Somebody said that UA called Medaire - no idea of the source on that - but as far as this context can provide, UA diverted the plane for medical concerns. Even if the "scratching" was not worded as to be a threat (which different news articles make it sound like it was or wasn't), individuals with autism have been known
to be self injurious, with self-scratching being one such behavior. So maybe the diversion is less heartless than others think.
The mom is taking full advantage of her fifteen minutes of fame for sure, but I think a lot of the capability to mitigate was failed on the parents part by failing to inform UA before flight time of their daughter's condition, failing to prepare or otherwise accommodate (e.g. rebooking) when their daughter refused to eat in Houston, failing to fly in a class of service that would ordinarily provide a hot meal, using the threat of scratching (whether in a self-injurious fashion or threat against the passengers), etc...