But...
The point of a democratic government is to debate an issue, vote on it, and then to enact the result of the vote. Representatives should weigh the information available, the points raised in debates, and their own consciences, and come to a conclusion of their own. Direct action like a sit-down protest undermines and subverts the process of democracy by saying "Do what we want or we'll make life intolerably difficult for you." That is not how government should work. Government shouldn't be held to ransom.
In this case it's easy to agree with the protest, but what happens if, say, the Republicans lose a debate on reducing income tax for millionaires to zero and organise a sit-in to try to get their own way?