No, only major announcements like they’re leaving the campaign to pursue a different line of work. Seems like good sense to me if not to Cruz geniuses.
What about, say, speculation that a candidate is not eligible to run for President? Should other candidates check that one out before circulating that rumor?
How about rumors that a candidate received "very low interest" loans for their campaign? Should those be checked out first?
Point is, your candidate will spread any news, any rumor, any bit of information--true or false, verified or not--about anyone who gets in his way.