You can’t have your cake and eat it too. If you withdraw your labor from an employer, and can’t act as though you have some ongoing exclusive right to provide that labor. By the same logic you provided, the organizers are harming the class of all people willing to take the employment on offer. When seeking employment, you have no onus at all to first check with the class of all potential candidates for that role to determine whether they all consider the tabled offer to be fair. The only judgement you have to make is whether you do.