First of all, no such thing exists.
In fact dapat isumbong sa DOLE, SSS at BIR yang kumpanyang yan kung
hindi properly compensated ang employees. I'm sure hindi din yan
nagbabayad ng SSS at nagreremit ng taxes.
Second, bakit siya mabablacklist? Ano bang kalokohan ang ginagawa niya sa kumpanya niya?
If leaving constitutes a breach of contract, there is NO LAW THAT ALLOWS COMPANIES TO HOLD EMPLOYEES BY THE NECK. Even employment bonds or those crap are just lip service -- I haven't heard of anybody who was relentlessly pursued by employers for leaving with an unpaid bond, and even if there were there are some employees who would gladly pay for a potential employee's existing bonds.
Seriously, I find this question preposterously... naive.
HINDI MO UTANG LOOB SA ISANG KUMPANYA ANG PAGKAKAROON NG TRABAHO. And if you're in IT, jumping from one job to another is the rule rather than the exception. Tell him to stop being a stupid martyr.