Which Lav is Dina D’malchusa? Unless Rav Belsky meant Geneiva, when Dina D’malchusa dictates who something belongs to or which rights he has. Whenever you’ll find Dina D’malchusa it is in this context. The Malchus has the ability to be Kove’a certain things. We probably depend on that for the Kinyan of checks and wire-transfers.
Tosafos in Bava Basra 2b learns that Hezek She’eino Nikkar means a Hezek that isn’t obvious, not necessarily that the loss is not physical. Therefore, planting grapes too close to someone’s field is a Hezek Nikkar, while putting a Sheretz on fruits is not obvious because we can’t tell if they are Muchshar.
Yekke, I think that about your case it just says that you can call him a Rasha.
Let’s not forget, Ve’asisa Hayashar Vehatov. This applies to Dina D’baal Metzra, Ani Hamehapech Bacharara and Hashavas Aveida Lefnim Mishuras Hadin.