He seems kinda lucky to me.
It's most likely just his engine, and his clutch assembly.
The reason his RPM's shot up is because his clutch didn't grab, and he most likely burnt his clutch to shit, not to mention, his engine is most likely fucked.
You are lucky that your clutch didn't catch. Otherwise, you would be out a tranny.
But, I would rather be out a tranny than an engine.
If the dealer just said that it's your tranny, then I go elsewhere.
Your oil light doesn't go on if you mis-shift and your tranny fucks up.
Also, in order to slow down, ever hear of engine braking, or putting the car into neutral, or even the brake itself?
Downshifting in order to slow down is pretty fucking stupid.