There are two points that are not clear from the rules. Firstly does the throne only function as a capturing piece if it is the king being captured or can pieces belonging to either side be captured by one opposing piece if they are positioned next to the throne? Second what happens if white can repeatedly threaten to move the king to the edge and black has only one piece that can block ie a forced repetition somewhat similar to perpetual check, in this case does the white side have to vary in order to avoid forcing the repetition or is the game considered drawn?
1) The throne can be used only to capture the king, not the "normal" pieces.
2) Yes, it should be considered as a draw but this site does not support a perpetual check detection yet. What you can do in such situation is to send a message to me and I will set a draw manually.