First let me say that I have never seen anyone guilded or not camping any spawn point and refusing to allow a player to kill a mob. maybe your problem is you like to hunt solo like me,well then you need to do it at a time when there is a low number of people on the server .
Best time for a low number of people on the server is around 3-4am EDT,numbers are around 50-60 people. So if you really want to hunt that mob and keep all the loot for yourself that is when you should hunt. At a prime time like Friday evening,Saturday,Sunday when there is a max number of people on the server chances are real good that someone is killing your favorite mob,but that is the way it is.
By the way I am in Builders INC and personally have never saw or seen any "nutty behavior" from Magoo ,strong opinions yes. So please,as we used to say in EVE when someone made a rant post with a noob alt account,"Can I have your stuff when you leave ???"