Even with more than 50 employees, that employer is off-base in his reasoning regarding part-time employees. There is a formula for figuring the number of "full time equivalent" employees. Add the total hours for all employees and divide by 30, so having two employees at 15 hours each is the same as one at 30 hours. He isn't saving anything. Additional employees increase administrative costs, but might give him more flexibility in covering his shift schedules.
Business operators need to base their staffing on making sure they have enough employees to take care of customers during their hours of operation. Cutting staff or staff hours impacts customer satisfaction and ultimately the profitability of the business. I hire employees to make me money. The more employees I have, the more money I can make. If an employee isn't making me money, then I don't need him. Profits come from knowing your cost of doing business and pricing your product or service accordingly. A level playing field makes for a more competitive environment. If I offer my loyal employees heathcare and the business down the street doesn't, how can I be expected to compete?
People need to stop blaming Obamacare for everything.