I don't think they are asking for additional liability by making the elders call them. Elders are already appointed by the WTS, so the WTS is largely going to be on the hook already for their actions that fall within the bailiwick of duties as an elder. It's whether the corporation can be held liable for the actions of a MS/ publisher that is murky right now. While an elder could seek personal counsel (doubt many actually would), they still can be required to call WTS legal, as least if they want to remain as an elder. It's no different than a corporation requiring that the manager of an individual branch call HQ legal anytime someone slips and falls on the premises. While the manager might potentially be individually liable as well (e.g. if she had failed to put up a warning sign for a wet floor) and therefore can get her own attorney, she still has to call the main legal department.
Of course, this is complicated by the mandatory reporting requirements for sexual abuse in many states. To use my analogy, if the corporation had a policy that the manager call legal before calling 911 if someone fell, they could potentially be asking for trouble. Though, with a business corporation, the attorney would have a professional obligation to make sure the manager knew he represented the company, and not the individual. I wonder if the WTS legal department informs the elders of this. Ethically, they should. I wouldn't exactly trust the ethics of anyone in WTS HQ any further than I could see them, of course.