Dear Parents (of a bright son),
At the outset, please reconsider the whole matter. What is the PSU? Why are you asking your bright son to quit a government job? Well, the PSU seems to be sick. Can't your son be that pillar who will enable a change in business/orientation of that company and become its Chairman/MD? He will get much more satisfaction of having served than what he can get out of several thousands/lakhs of crores of (paper) rupees. Well, India is still a kind society and all of us are allowed to take our own decisions. But, if you as a family stand with India under these circumstances, I am sure God will enable all of you such respect, happiness that you would not have even dreamt off.
Factually, industrialisation itself needs a revamp. There is an urgent need to re-orient India from whatever i.e. WHATEVER it is currently doing. If your son is an engineer with managerial skills and adroit in handling professional aspects that requires skills in multiple specialities, then he is amongst the rare few who can do that wonder. If you and your son can conceive things, aspects that can evolve new ways of livelihood that imbibes nature in, for all of its aspects in/for society and can have nature at its hub for all aspects right from planning to working aspects, then the plans will be as reliable as mother nature, God. You would be moving Gods yourselves. No force, it is for you to consider.
Coming to the legal questions that you have raised, if the bond specifies a period, an amount, exit terms etc; then there is no way that you can expect leniency in any of it. Well, if your son has been on study leave for as long as 10 years, then that period is not counted as service. That is all. Don't haggle around ID card, money etc; all of them will work as per law, terms and there will not be any injustice or liberal approach.
As yet another son of this great country, I want to humbly record something personal, something from the deep heart. I alone know the amount, the way that I struggled to get that government job right from 21 plus right upto 35, all with good qualifications, merit etc. But, CASTE, gender, lies, (dubious) lecturers/college/u'ty etc spoilt my chances. pErmanecy, multiple identities that others maintained, false caste certificates etc etc turned to be more pain. Now, I have a totally different, much more refined, much more higher, rather highEST vision in itself and am gearing up for all that. But, had I only got that opportunity at my right age, my life would have been different, my approach would have been different and I would not have endured so much of trouble.
Do think over, be kind to India. Yet, decision is yours.