I have a 2010 Ford Escape that the bolts on the front right(passenger side) engine mount have sheered. The mechanic is saying these are threaded into the timing chain cover and will require a new timing cover. His estimate for the work is $1400 and is claiming that the car cannot be driven until it is repaired (which I understand). Does this sound reasonable?

 

So the stud that goes into the timing cover has broken off and there is nothing sticking out the timing cover anymore? If so you could try an extractor but those studs are about 1-1/2 inches long into the timing cover and have threadlock on it making it very hard to remove, most likely would need to replace the timing cover and the stud. Depending on mileage you may want to get timing components replace while the cover is off.
What engine do you have? I assume the 3.0L since it was the more popular, I think I charged like 9 hours to remove the timing cover last time, had to EVAC & recharge the AC which adds some extra labor too.
Biggest thing would be to go over what all the mechanic will be replacing, if you want to replace timing components that is.