Watching the Event Unfold
It turns out that Chase saw how the older man acted toward Savannah and sensed that something was about to happen. He said there was no way he could let that man get away with his actions after witnessing the message written on the phone.
The Message
The message actually shocked Chase, but what worried him more was the man actually writing it. Later, everyone found out the old man sent a message to his wife, saying he had to sit next to a “smelly fatty” who “flowed over his armrest” to make him sick.