The permission doesn't prevent players from obtaining the items. Its not an admin plugin.
The only 2 permissions are deployablenature.admin and deployablenature.market.chat.
If you want to prevent anyone from obtaining the items via drops, set the loot values in the config to 0.
"Mining node drop rate [%] - [0 = off]": 1,
"Tree drop rate [%] - [0 = off]": 1,
"Collectable plant drop rate [%] - [0 = off]": 5,
"Chance for loot to be added to a minecart when it spawns [%] - [0 = off]": 10,
Setting these to 0 turns them off from dropping. Not providing players the permission to use deployablenature.market.chat prevents them from buying it from the market. This would effectively remove their access to it.