If resources matching any part of the building (as shown in the TC interface) are allowed to be added to the cupboard, then they will be used in the standard decay process. The way this normally has worked, and I am not aware that it changed, is that this bypasses the plugin altogether, at least for that resource.
Since you seem to want to block all resources, please also set blockCupboardResources to true. This may have changed as of the most recent update because of some discovered faulty logic in the plugin.
In short, if resources are in the TC when the decay.tick fires, we can't prevent the game from consuming those resources if they match any part of the building.
Also, make sure that you are using the version from this site because it is not compatible with plugins with the same name on other sites.