I think that 90 day re entry has always been there. Its a case of him cancelling his TVIP when he left Guatemala. He should have keep the permit open when he exited and said he would be back in a few weeks, they ask at the border if you will be returning at least they did for me. He can get a "in transit permit" to cross the country if he is heading south to other countrys.
Or......ride in discreetly and ride out discreetly.