You have a strange definition of "good kid". From your post we know that he: entered our country illegally, committed identity fraud, failed to file income tax returns and violated our employment laws. My guess is that he also probably broke a few other laws like: driving without a license, driving without insurance and probably more. Most illegals pretty much ignore any law that gets in their way. They only feel that they need to obey the laws that are not inconvenient for them to obey. They are not exactly model citizens and I have no desire to hand them the voting franchise.
As far as paying taxes goes, there is a big difference between filling out the form and actually contributing to the treasury. Employment taxes (SS and Medicare) are hard to avoid but most illegals list enough deductions so that income tax withholding is negligible. Now that he is legal and filing tax returns, he likely qualifies for the Earned Income Tax Credit (EITC) and is getting tax refunds in excess of whatever he is paying in. The EITC is welfare disguised as a tax refund courtesy of middle class taxpayers. If we do as you say which is to turn all these low income illegal third worlders into citizens they are going to be vastly more expensive then they already are for taxpayers because many will qualify for the EITC. They will get the whole enchilada: citizenship and welfare too!
How many illegals earn enough income to need to pay much in the way of income tax?