Antibiotics don't depend in any way on the genetic code of the bacterium, so it should make no difference initially to antibiotic resistance. However because its code is incompatible with other bacteria, it can't gain or pass on antibiotic resistance to others. So the antibiotic situation is better than nature. If you wanted to use bacteriophages (viruses which infect bacteria) to control them, an approach which is currently rare but might become common, you'd need a virus engineered for this bacterium, you wouldn't find a natural virus that could do the job.
If I were making such a critter I'd eliminate some genes that synthesized something important, then provide that something important to my bacteria colonies as a nutrient*. Then if any escape, they won't be able to survive in the wild. (I'd also use an appropriate level of bio-hazard containment. And I'd expect that some independent safety committee has OKed this research. However, that is all supposition - I have no direct knowledge of the safety precautions in this instance.
* Vitamin C is this for humans, except for the 'not present in the wild' part. Most animals can synthesize their own, but humans need to get it in their diet.