Not sure about the integrity of ISOM’s at any tourist spot but I can tell you that in old downtown Cancun near the bullfighting arena there is a small shop called Moctezuma where a woman has her rolling table and some really great local gars for sale. I really liked the Moctezuma brand, wish I were going.
... unless he gets it from an authorized 'La Casa del
Habano' ...
Do a 'Google' search, and it will give you the location, address and telephone number ...