I don't understand either...all rats do have feet! It sounds to me as if the rat was too large for your snake. Or was he trying to swallow it backwards?
The breeder may have been trying to accelerate his growth by feeding larger prey, so don't assume that what he was feeding was the right size for your snake.

For what it's worth, I've been at this many years & I've never heard of anyone coming back to a dead snake that swallowed wrong, though it's possible for a snake
to be injured from swallowing something way too big & then getting further injury from regurgitating it, but I'm just not sure what difference it would make if you
were standing right there...you can't pull the rodent back out when a snake is swallowing it. A snake CAN die from swallowing prey that's too large, it's just not
very common.