The problems with this line of thought are as follows:
- Career criminals don't really care about laws. Their options for procuring a firearm illegally range from making it themselves out of PVC pipe, a nail, and a rubber-band (although some "garage guns" meet or exceed the safety and effectiveness of professionally manufactured firearms) to buying off of the black market. And if all else fails, they can default to items which are, used properly (or improperly) quite dangerous, such as knives or baseball bats. The lack of a gun does not magically make a dangerous criminal into a law abiding citizen, as certain mentalities can always find something to use as a weapon, to deadly effect, no matter the situation.
- Reformed felons do care about laws. This means that, by choosing to reform, they are limited in their self defense options. An unrepentant felon will always have an advantage over a reformed one, simply because the reformed is no longer willing to break the law.
- It is effectively impossible for any single human to be aware of every single felony that it is possible to commit. Moreover, ignorance of the law is no excuse. Thus, it is entirely possible for generally law abiding citizens to commit felonies and not find out about the existence of the felony until the handcuffs are being applied.