Probably, but the law also allows you to kill your unborn child too. There is the law and then there is the LAW.
To heirs? That's very complicated. You don't know the relationship the man had to his children. It appears they didn't know a thing about the stash of cash which suggests he didn't want them to know about it.
Also, it's likely there was be a formal estate. The administrator of the estate, if you chose not to keep the cash acquired with the house, should've been informed of the money rather than children directly.
It's possible he may find himself owing taxes on it, even after giving it up, and the children could as well (either as a gift or inheritance). It depends how the law sees things. Was the money "his" by virtue of buying the home? If so, he owes taxes on it. Did he then gift the money to these other, unrelated people? It was certainly a taxable amount in that case too.