His party and also their coalition party are trying to keep the parliament together because if it gets dissolved then it's likely the pirate party will win in an election, so they're trying to avoid that.
First of all, if the parliament gets dissolved, the parties have really short time to actually prepare a campaign, which means that bigger parties will probably be more in a bit of an advantage, because they have a lot of experience. Pirate Party is not really big in Iceland neither, but according to the polls, it currently does have huge support (~40%).
Second of all, prime minister did try to dissolve the parliament by asking the president to do so before he resigned, but president rejected this proposal. This means that the parliament will probably be functional until the elections (set for autumn), just with a different Prime Minister. This gives the Pirate Party much more time to actually prepare for the elections, and, in my opinion, gives them enough time to actually crush the competition.
This is, by far, the best possible outcome for the Pirate Party.
