My guess, and it is only a guess, is that the value of the "return of premium" is less than neutral, meaning the insurance company gets more than their actuarial share of $$. The only real benefit is, if he lives to the end of that 30 yr period, then he gets his premiums back free of taxes. It doesn't show up in his AGI. This would have to come as an increased cost in monthly premiums. In exchange, he earns no interest on those "higher" premiums paid. As the COL increases, the buying power of those returned premiums, if he even lives to collect, decreases.
Can he easily afford to pay the higher premium, and will he need the extra tax-free $$ in 30 yrs? I'm sure, it can be shown to be better or worse by using different assumptions over the next 30 years. Just be aware that actual value to him can be far different than an Insurance company's illustration. There is no one right answer. It depends on DS's financial goals and plans.
As my daddy told me many times as I was growing up, "Figures don't lie, but liars can figure". Be careful.