Is Mechanic giving me a BS story?

[82 GT]

Yesterday, our POS Taurus's water pump went out. Since I hate working on those horizontal engines, I took it to the garage.
When my g/f and I went to pick it up today, she started it up and it wouldn't idle on it's own.
She said. "it never did that before". So starts looking around the engine compartment for loose vacuum hose etc. and finds nothing amiss. After keeping the engine running by working the throttle lever, it starts to idle on it's own again.
He said when the pump went bad and was spraying antifreeze all over the place, that antifreeze can do damage to spark plugs wires and could cause it to act like that.
He told me to take it for a spin down the road and back. It ran fine like it always did and stayed idling when I returned.
He said "yeah, antifreeze was all over the place when I brought it into the bay and probably has to all dry up before it will idle normal again".
Later on tonight after it cooled off, it was the same thing...wouldn't idle until after a few minutes working the throttle.
I think his whole story was BS. What do you guys think is
really wrong with it?(besides the fact that Taurus suck!!)