That's how telephones work. The "Bell Blue Book" specifies time-outs for disconnection. The Bell Blue Book was what phone systems were tested against in those days, and made a standard for phone operations nationwide. It's kinda hard for a machine (especially in those days) to tell when an intentional disconnect has occurred. This detection timing was important when pulse dialing was in use, since a brief disconnect might be interpreted as a possible component of a digit: they didn't want phone calls cut off because somebody accidentally knocked the dial. So call connection was mostly controlled by the A-party (caller), and there is about 10-20 seconds where the B-party (callee) might have hung up but the connection remains live. If the A-party hangs up, the call is disconnected almost immediately.

You can verify it yourself. Try it with your friends!

I suppose lying by her supporters is par for the course.

If the calling party does not hang up, IIRC the called party must hangup for 20 seconds to achieve a disconnect on a land line.

going by a 20 second google search - instinct says progressives of the moneymaking career variety as opposed to the philosophical variety but could be wrong