It does sound a bit harsh to me. No, MB2 cannot advocate for the others, especially if, as you say, they don't have friends in high places, but what she is doing is, hopefully, going to help a lot more passengers in the future because, by highlighting all the issues, P&O surely will have to listen to her, and other complainants, and try to resolve them for future cruises.
And, she did actually offer support to two ver elderly passengers, by getting them a taxi which, she, herself, was unable to use. I think she's gone overboard (excuse the pun) to be fair to P&O, while chronicling all the very many issues that have arisen - as I am only up to Friday's posts, I have no idea what, if anything, else occurs!