As someone who recently put together a privacy policy myself, I can assure you that an updating clause is standard practice for both privacy policies and terms

As someone who recently put together a privacy policy myself, I can assure you that an updating clause is standard practice for both privacy policies and terms of service. The documents are really mostly for minimizing liability. You can object to that, sure, but no sane company is going to open themselves up to lawsuits just because a few users are upset about it.