Aardman is probably a fairly hot company right now. Probably prime for a purchase by one of the big studios. But then it would most likely just get broken up and turned into a mill for churning out look-a-like content. Or possibly even just a logo stamped on contracted out content. I believe the founders have been fairly clear in the past about not being interested in selling.
While the founders still own it they can just turn down these offers and stay independent, but soon they are going to retire and will have to give up ownership to someone. And that someone might just decide to take the big payout and sell. So this is their way of ensuring that the company continues to run as it is for the good of the employees. It can now only be sold if the majority of employees vote to accept the sale, and if they do at least they'll also be the ones to get any associated payout not just some profit driven owner.