That doesn't make sense. If you're claiming that getting married in India is "not same like marrying in Canada", you're basically saying that he did NOT lie (which he did). Otherwise, why is he so worried/concerned now?Married where ? If you were married in India its not same like marrying in Canada. You lied in your application that you are single so you misrepresented which is the ground for losing the PR or even Citizenship. If you get married here in Canada and fill taxes together you will be OK.
Still suggest he talk with a qualified lawyer, instead of expecting those of us here to answer the questions.