Jobs would have had an estimate of what it would take to copy the feature - way less than $50m, just not quite as quickly.
It surely wouldn't have made a lot of difference (to Apple) if Jobs had laughed off the bluster, and negotiated back down to pretty much any number they liked, maybe even less than $50m.
But the asshole vibe from Jobs comes from the fact that he clearly didn't value the feature that much. It was more valuable to wait for his own team to build it slower, and send the CEO away with a flea in their ear pour encourager les autres. So I'm sure that story got heard by plenty of other potential Apple acquisitions, and saved Apple a lot of money down the line.