I believe it was $60 in additional labor costs, which I believe is highly unlikely since the academics who wrote the article had no knowledge of the manufacturing process. We just found out part of the process and number of steps to assemble and iPad, not all the steps to manufacture all the components.
The speculated cost of $60 more dollars in my opinion does not include the facility, and operational costs for a series of facilities.
As fas as supporting US jobs, you do support jobs at Apple, FedEx, UPS, and many others in the chain. The CPU I believe right now is made in Austin, Tx which has many US workers.
The labour cost is not the biggest problem. Workers' rights are, as well as logistics. In China, you can have a 100,000 workers work for 2-3 months, then let all of them go in a day.
Also, the whole industry is down there. If you need new screws, you have them in a day. Imagine how long would you wait for them to ship from China to the US or Europe.