<p>$100,000 in debt will constrain his options. For example, he may be required to chase the job with the highest pay, rather than take the job with the best career development opportunities. Of course, it can delay his financial goals (buy house or other things, save for retirement, start and support a family, etc.).</p>
<p>Also, if you use all of your money and debt(-cosigning) capacity for him, how will you explain to your later kids that there is no money for their college, so their choices are limited to big merit scholarship schools or CC -> local CSU?</p>