Except I'm not talking about one of the thousands of statements he makes a week. I'm referring to the immigration policy statement that is posted on Trump's website, which is one of only three policy statements on his website (the others being his tax plan and his second amendment plan). So, yeah, I would expect him to know what's in it.
Becky Quick was trying to show off her skills as a questioner. Also, CNBC have been up until very recently, part of the group that took Jeb Bush as the virtual nominee from his first announcement. So they are having a bit of trouble--internal trouble in their own minds--over Jeb's rapid disintegration. (Not excusing Becky's misuse of her position as a moderator. That was not excusable.)