Yes they should, and Presidential candidates should also have enough integrity not to make false statements. This is a statement that is easily proven to be false.
And therin lies my biggest single objection to Donald Trump. I’m not big on policy wonks with rehearsed speeches (like Rubio), but Trump’s knowledge of the issues is, by and large, only one soundbite deep. I’ve seen no indication that he has any sense of history or bothers to educate himself on the cause and effect relationships of the challenges facing America today.