Well, he can't, of course. But the President isn't delaying a law: the provision of the ACA at issue here -- the so-called "employer mandate" -- is self-implementing. Among other things, that means that no further administrative action (e.g., IRS regulations, etc.) is required in order for the employer mandate to take effect beginning in 2014.
Per this provision of the ACA, an employer with 50 or more employees must, beginning in 2014, either (i) offer its full-time employees health insurance or else (ii) the employer will be liable to pay a tax (or a "penalty"; call it whatever you like), the amount of which is derived from a formula that takes account of how many full-time employees the employer had in 2014 for which it didn't offer insurance.
Nothing that the Administration announced this week changes this; because the pertinent provision of the ACA is self-implementing, any large employer who doesn't provide insurance to its employees beginning in 2014 will, by operation of law, be liable for the tax/penalty for 2014. What the Administration has announced is that it won't seek to collect any such taxes/penalties owed for 2014.
It's hardly clear to me, since estoppel generally doesn't run against the government, that the foregoing announcement has any true force or effect in any event. That is to say, if, at the end of 2014, the feds turned around and told employers "pay up, you had X-number of employees for whom you did not offer health insurance," that the employers would actually be entitled to any relief whatsoever. As far as I'm concerned, by operation of (the self-implementing) law, they would owe the money.
I agree an employer could still be open to liability unless the Congress passes something.
Could not an employee sue an employer who does not fully implement it's responsibilities under the law one way or another? Either sue them for insufficient coverage or for not dropping said coverage altogether? I'd have to imagine any employee in such a company would have standing as they are directly impacted by it's policies.
So the administration says it won't take it's own laws seriously, yet the inaction would still place companies in legal jeopardy for inaction.
This is seriously the most incompetent regime I have ever witnessed or read about in history books.