I'm not sure what you mean with rolling the dice - it sounds to me like they're saying, the suppliers may have given antibiotics to the pigs as specific medical care, but are not just blanket giving every pig antibiotics. (The link says that permitting antibiotics for medical care is the one difference between Chipotle UK and US standards, in fact.)
Do you expect either lower-quality meat or higher-health-risk meat as a result of this? I don't think I do but maybe I just don't know enough here.
The short version in the Twitter screenshot doesn't fully explain the antibiotic issue. And it's the same one you see if you go to the restaurant personally. Given their history with E-coli (bacteria)[1], they need to be more explicit about what they mean. Making people sick nationally, with a bacteria, coupled with short critical quips about antibiotics is confusing.
The short warning just read to me as "don't order the pork, you might get sick". Not a great set-up for a good lunch experience. They seem to assume all customers are already educated about their sourcing strategy.
"the CDC reports a total of 55 people infected with the outbreak strain of STEC (Shiga toxin producing E. coli) O26 from a total of 11 states in the larger outbreak"
"Chipotle Mexican Grill closed 43 restaurants in Washington and Oregon in early November 2015 in response to the initial outbreak."