That can't be a valid argument in this case and many others people share. The US workers that are being laid off are so proficient that they can train their replacements. The problem is that the foreign replacements are mostly much worse at programming.
There was a stat last month that somewhere around 50% of US workers with STEM degrees can't find tech jobs. And you know what? The STEM programs I saw in the public schools are pretty good.
Training replacements describes a variety of functions including everything from the procedures for production, testing, turnover, data dictionaries, file structure and overall systems knowledge and other information traditionally found in documentation but not always kept up to date. Training is likely not simply programming/configuring. There’s also the possibility that the company needs to update/upgrade systems/environment/languages and to do so will require retraining in the new software or environment. This can be very expensive and frankly not all workers are good candidates for retraining. IT involves frequent changes to technology and, as surprising as it is, many in IT don’t keep up on these advancements.
Workers may have degrees in IT, but that does not mean they have the skills employers need. In my experience recent college graduates generally are poorly trained and need, on the average, 6 months to a year of training before they can be of much value to the employer. There was a very good industry article about this about a year ago. As I’m on a tablet atm I can’t easily search for it, but if you’re interested, it shouldn’t be too tough to find.