Silencing someone should never be the goal. If the Conversatives are experiencing difficulties pushing through their agenda due to opposition from other parties, then the best way to resolve that is either via compromise or by calling an election to increase their majority in parliament which should allow them to push through their agenda more easily.
Even if (arguably especially if) the Conservatives win 99% of the seats in the House of Commons, the remaining 1% should be opposing, scrutinising and holding to account as well and as loudly as they can.
Yet Theresa May is after something different here (a tactic which we've heard recently, but by no means exclusively, from many Brexiteers as well) - she is implying that unless opposition parties can beat the Conservatives in a general election, then they should put up and shut up as the public have spoken.
That's not how democracy works.
-----
edit: For those who don't see the straw man here, it is that while silencing someone who is standing up for the beliefs of people who don't exist is okay, in real life the parties who are currently opposing the government are guaranteed to be defending a none-zero number of British citizens, who we cannot allow to be silenced on principle (even if we act against their wishes).
The Lib Dems campaigned for an EU referendum [1], and now want to reverse it because the result wasn't what they wanted.
The SNP campaigned for Scotland to leave the EU (as it would have done if leaving the UK) in their independence referendum, and now behave as if leaving the EU is unthinkable.
Both are playing politics. The ground has shifted, and so it's helpful for the government to get a new mandate.
[1] http://www.newstatesman.com/sites/default/files/images/Clegg...
