Hi OP part of my family comes from one of the main olive oil producing areas in the world. I visit often. I have never seen, heard or read about the vacuum method. The usual method is for the tree branches to be shaken, then the olives fall down and are gathered on a net or cloth. The branches can be hit with canes to make them shake or a special machine is used to do the shaking.
I am also baffled by the claim that millions of birds roost or rest - not very clear from your link - on olive trees. I would love to see how the figures of millions of victims were calculated. Being familiar with both birds and olive trees I cannot get my head around the whole thing.