According to the Duden, comparative clauses like yours can be used with Konjunktiv I or Konjunktiv II. Usually, we use them with Konjunktiv II, but in your case, Konjunktiv II would be the same as Präteritum, so Konjunktiv I is a better choice to express that he is NOT the hotel owner or at least we are not sure whether he is or not. He acts as if the hotel _belonged_ to him. (It probably doesn't.) http://www.duden.de/sprachwissen/sprachratgeber/nebensaetze-mit-als-ob-als-wenn-wie-wenn

I'm so stressed out. I don't know what any of the terms are your saying!

Generally conjunctive means not real action. (the verb is not done in reality) It will be mostly used to indicate indirect speech. In the mentioned example: Das Hotel gehört Thomas nicht. Aber Thomas verhält sich als ob das Hotel ihm gehört.