Being a good tailor doesn't mean you're wrong for taking a loan from a criminal. It looks like he earned that loan, a sign of confidence and trust in quality, from Mr. Big by being able to produce a quality product. We don't yet have the full story, but so far it's looking like something he shouldn't have any problem with.
Love all the headcannons with introduction to Mr. Big, and backstory of Nick and his father. I also think I understand the title of the story, 'It Should Have Been Me.' It's Nick's father stating that he should have been the one to get Nick on the right path, rather than waiting for so long, and having Judy do it for him.