Why hold it a month ago? There was still time to negotiate.
And answer if Greece was supposed to accept the last proposal without having the population vote on it, just because now we were closer to a deadline? You can see how clearly it was disingenuous of the Troika. You are saying Greeks should not vote on a proposal that is handed close to the Troika's own deadline, that they should just sign it.
Tsipras is right, it's an affront to democracy.
If Greece wanted a referendum, they should have gone to the other parties and said: "Look, we need our population to vote on this, so let's make a proposal in time and have them vote before the deadline is passed." I don't know why that is difficult to understand.
Voting on it is not wrong, although you can argue that by voting for the government, the Greek people have already given them the right to make a deal or not.
What you can't do is just come in the last day and say you are putting it up to a vote
after the deadline.
And yes, closing in on a deadline is increasing pressure. That is how deals work. If Greece wanted to prevent that, they should have worked out a solution long before the deadline, which was already known to them for a very long time, ran out.
As far as i know, Syriza has already stated that they would obey the referendum, regardless of the outcome. No reelections necessary.
The problem here is Syriza does not want the deal to happen. So if they are forced to by the people, how can they be trusted to work out the details in the best way if they are against it. If Greece votes to agree with the proposal (if that is even being accepted by the other parties involved...) Syriza has to step down. It means that between the election and the referendum, the Greek people changed their mind on implemented austerity.