Notice how when someone goes ‘down’ in the polls they complain about something Trump says, Trump responds and the value of the complainer goes up.
Carly said something ‘cute’ about Trump, Trump responds, and Carly gets to say ‘Trump is picking on poor little ole me’.
Apparently Mr Walker didn’t have to sign any pledge as his remarks upon departing could be taken as ‘anti Trump’.
If Trump drops out and goes after RNC, GOPe, the remaining candidates, they will collectively sue him for ‘breaking the pledge’ and not openly kissing their arses on his departure.
The pledge is NOT legally binding.
The pledge is pretty meaningless, but the sore loser laws are not. Apparently those are on the books in many states and the longer he remains a GOP candidate the harder it would be to build a brand new organization down the road if he wanted to go 3rd party (which I think he'd want to do if it looks like he might lose in the early primary states).