"the Bolsheviks fuctioned practically on the basis of frequent public disagreements. During the July Days, while the Central Committee was urging calm, the St Petersbury Military Organisation used its own independent press to call for action."
A good point and of course Lenin argued openly against the majority line.
Anyone should be able to argue whatever they like of course- but there may be times when if it undermines action then it is appropriate under exceptional circumstances to part ways with someone.
An example- if a strike is called and voted for and acted on and takes place then is members of a socialist party or organisation say it was mistake for tactical reasons that may well be fine. If they still undertake the action but argue for a different course- perhaps extending it or waiting for other sections of workers to join in they should have the right to do so within the organisation and publicly. If however they then say we should break the strike they have of course the demoratic right to say that but they should be expelled and indded prevented from crossing the picket line. Or if they take up arms agianst wokrer sin struggle we shoudl fight them. These sort of extrem cases that should lead to expulsion.