Actually a medical evacuation can cost $100,000 or more so the insurance salesperson at Carnival needs to get up-to-date on her information.
As you said - it's your choice and you seem to understand what you are risking. I always buy coverage and that is my choice. One thing I never do is buy the cruise line's coverage since it never seems to be as good as 3rd party coverage.
This is the first I've heard of this type of sales tactic. They were way out-of-line in my opinion, and especially given it is 2 weeks out from your cruise it seems a bit late to be pushing insurance on you.
And what does being over 60 have to do with it? Anyone could require a medevac no matter their age.