Candidate used work email in recruiting process, deal breaker?

I have a candidate that made it through multiple rounds of interviews and every person who spoke with her absolutely loved this candidate. She has a great personality, driven, and is incredibly intelligent. However, she is a recent graduate and has room to grow / needs to learn the "unspoken rules" of the workforce. For example, she used her current employer's email to send thank you emails and work samples to myself and the team. I chalked this up to her being "green" and this is something she needed to learn. I even had our recruiter reach out to let her know moving forward to not use that email address since it could send the wrong message. This role is an entry level role for a department that I manage. This wasn't a deal breaker for me since it's an entry level role, we can't expect polished candidates out of the gate. The VP I report in to always wants to screen candidates regardless of the level of the role. Her using her work email was a deal breaker for him. I tried to make the case to defend hiring her and that didn't go over well. Now I'm in the situation where I have to pass up an incredible candidate for a lapse in judgement (we've also been hiring for this role for 3 months). Any suggestions on how to move forward? Is it worth making the case even further to my VP? Or is this a definite no-no in your eyes?