Trump took Walker out just as he took poor old Ben Carson out.
The difference is: Ben went to him believing Trump would reward him.
Scott Walker endorsed Cruz.
http://edberry.com/blog/polymontana/player/donald-trump/an-open-letter-to-mark-levin-trump-vs-cruz/
An Open Letter To Mark Levin: Trump vs. Cruz
snip
A little background:
“I lived in Wisconsin during the Reince Priebus reign of terror when he was the State GOP Chairman. Ill bet not a lot of people know about his former life. Ask Former Congressman Mark Neumann, or any of the other Gubernatorial candidates, what happened when they dared to run against The Chosen One, Scott Walker, for Governor in 2010. Ask Michael Steele what happened when Reince Priebus decided he wanted Steeles RNC Chairmanship. You can also ask Mark Willis the same thing, from 2013....”