Because right now, this thing will be PERMANETLY dead within fifteen months, if Congressman Billybob is right. From what I've gathered about his resume and his experience, his confidence does not seem to be unfounded.
Since the Supreme Court cannot issue advisory opinions (again, ask the good Congressman if you do not wish to take my word for it), the only way to kill it permanently is to let it become law.
There's a difference between a principled stand and the political equivalent of Pickett's Charge.
I want the president and the congress to do what they swore an oath to do.
If the oath to uphold the constitution means nothing to Congress and the President then they can draft similar legislation till the end of time.
There is no gurantee that this is the end of CFR like bills. None.
And, if anything the knowledge that the President will sign it and the media will fawn over them is an incentive for Congress to try again.