[A.A. Cunningham]

but when their wives die, if they want, they CAN enter the priesthood.

Incorrect. That's why it's called the Permanent Diaconate.

[SuziQ]

I believe there have been several ‘Permanent Deacons’ who, after the death of their wives, went on to join the priesthood. It’s not an automatic thing, but at that point, they’ve already completed some of the steps.