First off: By no means am I discounting your concern or suggesting you did anything "wrong" by your post to the Requests for Advocacy page.
Advocacy's purpose is generally to get involved with disputes between users. The more specifically defined the dispute, the more clearly it can be dealt with. A dispute between two active, registered users is the cleanest cut; an explicit dispute between a registered user and an anon is less clear cut, a passive or tacit conflict between a user (such as User:The Mule) and non-engaging anons is less clear cut, and so on.
It seems pretty clear that Quixtar is the target of vandalism by anonymous sources who deliberately want to inject or emblazon anti-Quixtar sentiment onto Wikipedia. It is pretty doubtful that you will get any of them to a rational discussion level; certainly they don't honestly think that Scamway and Quixscam are the real names of these companies, so I wonder what sort of rational discussion could be had with them on the topic.
When it comes to acts of anonymous vandalism, generally the convention seems to be that more responsible users revert the vandalism to the previous non-vandalized version of the page. (See Wikipedia:How to revert a page to an earlier version.) Page protection is pretty uncommon, and will probably only be granted if constant, highly repetetive vandalism can be shown. In this case, I don't think the level of problems is at the level where protection would be granted.
You can certainly join in with the efforts to undo the vandalism by adding Quixtar to your watchlist, and when you see it come up as edited recently, especially by an anonymous user, clicking the "Diff" or "Hist" links can lead you to see the changes that were made, and how far back to revert the page to a non-vandalized version.
To revert a page, you can click the date and time link of a known-good version of the page, and then Edit the page you are taken to. A blurb at the top of the editing page will alert you that you are editing an outdated version of the page -- this is what you want. Without changing anything in the edit box, you should add a note to the Edit Summary (e.g. "revert vandalism to last by User:The Mule"), and click Save. This will reapply the last known good version of the page as the current page.
If vandalism to the page becomes far too much to handle this way, then Wikipedia:Requests for page protection may be your next step.