That argument is horse shit (nothing personal). If an employer needs to hire someone for their business to grow, they hire someone, Obamacare or not. If they don't hire, the business stay's locked in place and there will be no increased profit. so they hire and pass the cost on to the consumer. That's the way it has been forever, and always will be. Although the Republicans love to roll out that job killing crap anytime they choose, it just isn't true.
I don't think you're connecting all the dots. We're not talking about just paying for the 50th employee's health insurance, we're talking about existing employees too. An employer's present costs plus the added costs that would result from hiring a 50th employee might not justify adding the employee, even if doing so would increase revenue.
We can work the math out. Let's say I have 49 employees and want to hire a 50th. If I do that, I trigger the employer mandate. Let's presume that I choose to pay the fee rather than buying insurance for my employees (which is probably more expensive). The fee would be $40,000, which means the 50th employee has to add $40,000 in revenue, plus whatever they're earning, plus some degree of profit for the business. You can spread it out to two, three, four, five, or more employees if you'd like, but for most businesses that added cost would be prohibitive.
I agree with your observation, of course. The prospect of this additional tax is going to leave a lot of small businesses "locked in place." Hiring more than fifty employees will now come with considerable risk, because you'll be on the hook for the tax as long as you've got them even if the expansion doesn't work out. A lot of owners and managers aren't going to be willing to take this risk.
Your suggestion that the cost is just going to be passed along to the consumer is wrong because this isn't like an excise tax on cigarettes or alcohol. For example, let's say that there are two restaurants: one hires a 50th employee and passes $75,000 in costs along to is customers while the other stays at 49 employees and keeps its prices the same. All things equal, the second restaurant is now going to do more business because it has lower prices.