It depends. Attorneys and lawyers can and do take cases representing opposing sides all the time (from one case to the next). It's pretty much a requirement they be able to represent their employer (without personal bias, etc.) It's what allows them to defend indefensible people like, say, murderers --it's not that the lawyer believes in murder, but they are paid by someone to represent the murderer, for example.

So, unless we think they are acting as moles in the DoJ, I don't see much issue with it, unless they have a conflict of interest such as being an investor in the industry or the like.