It's a catch 22 for Chipotle. Either you source local and prep in house or establish a foolproof centralized system. Either way have risks.
What really needs to be delved into is why this only seems to hit Chipotle and not Subway, Jimmy John's, or other competitors. I'll be blunt and say that those of us with food industry experience look at warmers that hold meat all day long and shudder with fear. All other sandwich type shops either keep the meat cold or cook to order. Add onto that the risk of all the tools and employees handling said meat. It's a real nightmare.
If they consulted me step one would be to reduce the batch size of all the meats and develop some kind of "clean in place" system for the meat to prevent cross contamination (which gave me the spooks the 2 times I've eaten there). I'd also reduce batch size for veggies and require sanitation between batches. I have a strong suspicion that a lot of tainted veggie problems stem from one knife and cutting board being used all day. Bottom line I want small batches with rapid turnover and improved sanitation. Do that and you keep the local sourcing. If you need bulk ingredients and can't follow the rules, time to call Sysco.
Everyone in the food industry saw this coming a mile away. There's a reason you don't do fast food with "slow food" ingredients. As I write this, bear in mind that no one, not you, not me, no one could pass a food safety inspection in their home kitchen. What keeps us safe at home is low volume and the long idle times between kitchen uses. Imagine how filthy your stovetop would get if you kept your cast iron pan hot and cooking from 10 AM to 10 PM every day for a week. Industrial food requires systems for this reason.