Because there's a 99.999% chance that he was doing what any other kid would do in the same situation with a cellphone capable of doing that would.
It doesn't send any signal back to his masters, whomever you might think that would be.
Where is the evidence of a Chinese/Palestinian terrorist group? Or that either group would gain by shooting up an American university?
This kind of speculation drives me nuts.
I don’t buy the “signal” hypothesis but a simple “success” message doesn’t seem outside the bounds of possibility. Impossible to differentiate from an innocent recording. If he was from a “well-known Palestinian family” then I think a run-through of his email records isn’t unreasonable.
If this creep wasn't a Muslim, the next one likely will be. What was that school in Russia where Muslims murdered all those children?