I am presuming the information we have or use here is what we have heard via the media, the media seem to suggest the mp's vote for him was very weak, so why would the mp's who are "throwing their toys out the pram" hang around for a party leader whos views/policies they dont agree with and more over someone who they think will damage the party?
I think the biggest surprise is that an mp has the integrity to follow their believes, not blindly back a leader they have no faith in.
If you put something up for a vote, you have to accept the result. Particularly when it's so overwhelming. He took 40% more than the next candidate with 250,000 of 420,000 cast. That's a mandate by any standard even if you believe 1000s of secret Tory voters snuck in.
If the losers don't think party members are "right" then it means their either wildly out of touch with your the supporter base or they have no respect for what they've decided (or more likely a bit of both)