They're emboldened because the new Republican supermajority in the House has telegraphed its fecklessness to the Democrats. The House GOP leadership has latched onto House Rules as a fig leaf to cover their cowardly failure to address the $105B already allocated to ObamaCare.
Now the Democrats know there is no threat to ObamaCare on its congressional flank, so all they need to do is drag out the judicial proceedings (i.e., trying to "tell" the Supreme Court not to accept a direct appeal) long enough to get it good and entrenched in the bureaucracy and it will be damn hard to dislodge it.
The House GOP leadership planted a dagger deep into the backs of everyone who gave them their new majority. I hate them.