There were in fact some people who worked at banks who refused to participate in the fraudulent lending activity, falsification of income statements, no-doc loans etc. - they quit or were fired.
It may be "reasonable" to engage in fraud when the government is enabling it - but its not honest. Hopefully our country can come to a point in the future where being honest is viewed as the "reasonable" thing to do.
If that's all that you did then you'd be fine (everyone else is of course another story but business is business).