I'm not saying it is necessarily the case here, but if the implication is that Ferentz is being hypocritical by visiting a committed recruit, then I would have to say that the accuser is misinterpreting the "rule."
Unless they are explicitly told no by the recruit, it is understandable and expected that programs will continue to recruit players that have given verbal commitments to other programs. Many players "up their stock" after committing, opening up avenues to higher profile programs. Iowa, like any program, has the right to reach out.
What the Iowa coaches are basically saying with this rule is that if a player does make the decision to commit to them, then they are expected to honor it, and, knowing so, the Iowa staff will back off on recruiting players from the same position unless the intent is to sign more than one. To honor that two-way commitment, the player is told not to visit other schools unless given an exception. There is always the option to decommit, then take visits, but don't state that you are committed, then visit other programs without permission (a la, Benjamin).
The Iowa coaches are very good about being upfront and encouraging players not to commit unless they are 100% sure, and emphasize that it's a 2-way street.