Sure the agreement was one sided, and maybe it even had questionable legal basis and would be unenforceable, but guess what, so do many other contracts consumers sign every day, and those don't usually net us $50k!
If the author had another job lined up already, the severance package wasn't worth much of anything -- it only paid out until he had a new position. So, probably closer to passing up $0 than to passing up $50K.
Still a bit of an annoying personality. If you know you won't get any $ from the severance package, just send a "thanks but no thanks" message to the person off-boarding you. Don't harass some poor corporate lawyer 2 years of out law school with inane demands for preferential terms on the severance contract for an individual contributor.