You are mistaken. Tier 5 tanks are available to be created by everyone; this page in particular is merely Patrik's own documentation of his own take on Tier 5 tanks and how they function. Not all Tier 5 tanks are under his ownership.
Due to moving and vacation, I will be on Hiatus for the next two months. I'm not exactly sure when I'll resume full activity, but it should be sometime in late June or early July. I'll also be on occasionally during the next few weeks, but not at my normal activity level.