I'm guessing Walker gave a "non-answer" to a loaded question from a reporter seeking to back him into a corner. Happens all the time, especially with the abortion issue.
Getting caught up in a media created "controversy" only works against the real work a person is trying to do. All Walker has to do if he decides to run for president is give one policy speech detailing his stance on illegal immigration and the borders and then refuse to answer any and all "what if" questions pertaining to his already stated beliefs. Same goes for abortion or any other subject the media uses to create controversy in a campaign. Remember, the media never uses this tactic on liberal candidates. It is foolish for conservative candidates to allow themselves to get sucked in.
It is also foolish for people to not recognize political strategy employed by candidates avoiding these pitfalls.
I think you hit the nail on the head. It’s not like Walker’s response to a loaded question was terrible. He isn’t Jeb Bush who has argument for amnesty on Hispanic news networks and made policy speeches arguing the same.