Retirement planning is generally a joint issue which is why the courts tend to view it as such. Spouses may choose to overfund one partner over the others for better investment choices in a plan, better company match, or a number of other issues. And traditionally, if a family chooses to have a parent stay home for one reason or another, it is statistically more likely to be the mother. This is why most pension plans won't even allow a participant to choose single life instead of survivor life without a sign-off by the spouse. For many, many people, making sure your family is taken care of once you're gone is very much their problem, hence the popularity of life insurance.
Legally, sure. He was entitled to do what he wanted at that point with his money, but morally? I think he was being selfish, though probably out of shock/fear.