When reordering pages in admincentral the info.magnolia.module.templatingkit.sites.TemplateAvailability#isAvailable check is done with a temporaryNode that has as parent the node that the node to be moved is moved below.
So for example I have a set of nodes under a NewsOverview when I move node 'News01' below node 'News02' the path for the check is 'News02/temporaryNode'.

This is incorrect, it should use the parent (the overview) node of node News01 as that is the parent that the node will have after the move, it will not be a child of News02.

Because our templateavailability disallows news pages as parent of news pages this does not work.