Urgent help regarding offer

Dear WSO Family,

I need your urgent advice. I have a full time offer with the Public sector group of a Consulting firm, I just realized that they do not hire permanent residents for that group, and I am a permanent resident, this issue never came up during the interview and application process, and I never misrepresented any fact on my application or during the interview, I just realized based on conversation with a friend who talked to a recruiter in the firm about internship opportunities within the group, what do you advise me to do, I really don't want to lose this opportunity and I also don't want to be black listed by the firm, I haven't discussed these directly with anyone as of yet.
What do you think I should do, and also do you think I can talk to them to transfer me from Public sector to Commercial where citizenship is not a requirement; it is so sad that I will be becoming a citizen next year?