But some of the protesters, including Blair, then went to another building on the company's property, known as the annexe.
Staff member Peter Alkema, 60, was in the building by himself.
When Blair and some others tried to enter the building Alkema tried to push them out. A scuffle ensued, that ended with Blair spitting at Alkema, hitting him in the forehead.
Judge Mary O'Dwyer took aim at Blair's actions while convicting and sentencing him.
"I find your actions towards Mr Alkemer to be arrogant and dismissive.
"You have a sense of entitlement about your behaviour on that day, and you showed no respect throughout the whole of the proceedings today towards the people who have been affected by your actions.
"You believe that you have an entitlement to do that because of your beliefs.
"But it's plain to me that Mr Alkemer was very badly affected by that, not surprisingly in my view, and that he felt insulted by being spat at.
"You now have two convictions against your record, and that in itself is a very serious penalty.
"You carry those convictions not for something that you should be proud of, but for something you should be remorseful and regretful about, to spit at a person like that.
"I would have expected you would be remorseful about that, and take some steps to make reparations for that, but you have not."
Blair had said the spitting was in self-defence after Mr Alkema punched him. But Judge O'Dwyer said the evidence for that was "implausible".
Blair was fined $500 for trespassing, and ordered to pay reparations of $500 for the assault.
Fellow protester Laura Drew had also faced trespass charges, but her charges were dismissed as there was evidence she left the first building when the protesters were told to leave.
