Loyalty in a free market is a pipe dream. Extremely few employers will stay loyal to their employees when times get rough, say when an employee gets very sick and can't work for several years. Thus no rational person should have any long term loyality to an employer if the market providers better alternatives.
This is a big reason why a US company might prefer immigrant workers. Local workers tend to treat their jobs more as transactions and less like a relationship with their employer. Immigrant workers come with built in motivation to stick to their employers and stay loyal.
