A criminal defense attorney would be used to being on the other side of the govt. I would be surprised if that were a problem. Also doubt the blue chip firms do much, if any, work for the City of Baltimore. Not likely the city can afford them.
Let’s say you have a huge law firm with a criminal practice as well as lots of other areas such as business. Hard to believe that city lawyers would hold a grudge against all the lawyers at the firm because the criminal people did pro bono work on a case.