PO is trying to force Mr President Duda to accept two judges they chose
All mixed up as usual: PO appointed five judges. According the the rules set out in the constitution three of those were properly made and two weren't. Nobody wants the two improperly chosen judges to be sworn in as fas as I know. The three properly selected judges should be sworn in - to not do so is to violate the constitution.
But why did PO supporters didn't say a word about what former govt did and they're vocal now?
There wasn't a verdict before now? No one is now defending the two judges or PO for chosing five instead of three , it's the three that were selected in accordance with the constitution that are the issue.
In practice they're going to pass Constitution-breaking laws without having the required majority.
Exactly. It's rule by party (as in most of the time of the PRL) rather than rule of law. Those who support the current PiS policy vis a vis the constitution are technically traitors since they're putting their political allegiance ahead of the constitution.