Does it not strike you as a questionable strategy to mount a suit that, if you win, you get what you don't want?
The idea of the House suing the President is bad enough. But creating a situation where, if you win, the people lose seems absolutely absurd.
Obama has delayed several parts of Obamacare for one reason only: those provisions are politically toxic.
Forcing their implementation is the best way to build public pressure to bring down the law altogether. Otherwise, he can pick and choose the provisions to implement and as time passes repeal becomes more and more difficult.
Furthermore, if Halbig holds, the Employer Mandate will only be triggered in those states that have established their own exchanges, meaning that the people in mostly Democrat-run states will be yelling the loudest, telling their governors/legislators to dump their state-run exchanges so they, too, can keep their employer-provided insurance.