In a typical situation, no. But this is very much atypical. The person in question has a guaranteed source of long-term income. It's better than any job; they'll never get fired, or get fed up and decide not to come in anymore. It sounds like you can even redirect the payments so they go directly to the company making the lump-sum payment. The only risk is bankruptcy by the payer. It ought to be safer than a high-quality mortgage or car loan, which right now are available at 4% or less. (My car loan is 1.11%, which is completely ridiculous and not all that unusual.)

"It may make perfect sense." I didn't say it makes sense in most situations.