Again!! if he's primary responsible for his children, still he can apply but his child also must be lived with him in Canada, when he completed 18 months, eventually his child too, which means both of them are living in Canada for 18 months, his wife not required to be in Canada and accomplished 18 months here in this situation.
But that's not his case here, he said his family joined him only 7 months back, I assume his wife and child, both joined him, if his child already lived with him then he can claim CCB saying he's primary responsible.
Everyone can apply CCB ONLY if you meet all the above mentioned conditions, I wish him to apply and let him know if he's eligible or not. All I'm sharing here is the process I had already gone through and am availing CCB. All the Best for your conditions too to meet
@Das67 the eligibility.