I doubt it very unlikely that the purpose of this site is to sabotage other guilds.
First of all, the site creator has a very clear link to his guild at the bottom of the main page. So it is very open and transparant to everyone who is running it.
Secondly, hosting a site with this amount of traffic isn't free and cost a lot of money. So I doubt it highly unlikely they are using it with the purpose of sabotaging things.
Thirdly, your claiming that they are representing them as the number one resource. I think that claim is wrong as well. for example on the Guildwars 2 guru website, they just advertised their site in the appropiate forum and the mods there decided to link it in a more prominent place.
furthermore I would like to stress out that this site should only be used as an indication but I doubt the impact will be as big as some people claim it to be. A lot of guilds didn't publish there whereabouts there or not their member count. For example. Gunnar's hold is currently showing as the numer 3 eu server. However. One of the guilds there is [KISS] and although I don't feel a lot of love for [KISS] I think everyone agrees that they are huge. They didn't publish info there bout their membercount. But knowing a thing or two bout it, it means that Gunnar's would beat the others in member count after that (and that is just one example).
The information is far from complete and is therefor only a good indication of what is really going to happen.
Last of all I wonder why you are posting this here. This is the guildwars 1 community. We got nothing to do with guildwars 2. I symphatise with your quarrel with the makers of that website. But making a post like this on a semi-related website that is also fan based is in my opinion out of line and tells more bout you then bout this website.